Libunwind: build libunwind with rust bindings

src/Cargo.lock

@@ -35,6 +35,12 @@ version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 
+[[package]]
+name = "cc"
+version = "1.0.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7bbb73db36c1246e9034e307d0fba23f9a2e251faa47ade70c1bd252220c8311"
+
 [[package]]
 name = "cfg-if"
 version = "0.1.10"
@@ -209,10 +215,18 @@ dependencies = [
  "volatile-register",
 ]
 
+[[package]]
+name = "libc"
+version = "0.1.0"
+dependencies = [
+ "cc",
+ "libboard_zynq",
+]
+
 [[package]]
 name = "libcortex_a9"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#ec252b099cf67a51ba9daa72b3292db8c21ba1b8"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#6195ad40c334a847cd01cd4adadf6b8f8d730908"
 dependencies = [
  "bit_field",
  "libregister",
@@ -369,11 +383,13 @@ dependencies = [
  "futures",
  "libasync",
  "libboard_zynq",
+ "libc",
  "libcortex_a9",
  "libsupport_zynq",
  "log",
  "num-derive",
  "num-traits",
+ "unwind",
  "void",
 ]
 
@@ -416,6 +432,16 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
 
+[[package]]
+name = "unwind"
+version = "0.0.0"
+dependencies = [
+ "cc",
+ "cfg-if",
+ "compiler_builtins",
+ "libc",
+]
+
 [[package]]
 name = "vcell"
 version = "0.1.2"

src/Cargo.toml

@@ -1,7 +1,9 @@
 [workspace]
 members = [
+  "libc",
   "libdyld",
   "libcoreio",
+  "libunwind",
   "runtime",
   "szl"
 ]

src/include/stdio.h

@@ -34,6 +34,7 @@
 #define __need_NULL
 #include <sys/cdefs.h>
 #include <stddef.h>
+#include <printf.h>
 
 /* typedef only __gnuc_va_list, used throughout the header */
 #define __need___va_list

src/libc/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "libc"
+version = "0.1.0"
+authors = ["pca006132 <john.lck40@gmail.com>"]
+edition = "2018"
+build = "build.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libboard_zynq = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
+
+[build-dependencies]
+cc = { version = "1.0.1" }

src/libc/build.rs

@@ -0,0 +1,40 @@
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    libc::compile();
+}
+
+mod libc {
+    use std::path::Path;
+    pub fn compile() {
+        let cfg = &mut cc::Build::new();
+        cfg.cpp(false);
+        cfg.warnings(false);
+
+        // still have problem compiling the libunwind
+        cfg.flag("-nostdlib");
+        cfg.flag("-ffreestanding");
+        cfg.flag("-fno-PIC");
+        cfg.flag("-isystem../include");
+        cfg.flag("-fno-stack-protector");
+        cfg.flag("--target=armv7-none-eabihf");
+
+        cfg.flag("-std=c99");
+        cfg.flag("-fstrict-aliasing");
+        cfg.flag("-funwind-tables");
+        cfg.flag("-fvisibility=hidden");
+        cfg.flag("-U_FORTIFY_SOURCE");
+        cfg.define("_FORTIFY_SOURCE", Some("0"));
+
+        let unwind_sources = vec![
+            "printf.c"
+        ];
+
+        let root = Path::new("../libc");
+        for src in unwind_sources {
+            println!("cargo:rerun-if-changed={}", src);
+            cfg.file(root.join("src").join(src));
+        }
+
+        cfg.compile("printf");
+    }
+}

src/libc/src/lib.rs

@@ -0,0 +1,15 @@
+// Helper crate for dealing with c ffi
+#![allow(non_camel_case_types)]
+#![no_std]
+
+use libboard_zynq::stdio;
+
+pub type c_int = i32;
+pub type uintptr_t = usize;
+pub type c_void = core::ffi::c_void;
+
+#[no_mangle]
+extern "C" fn _putchar(byte: u8) {
+    let mut uart = stdio::get_uart();
+    uart.write_byte(byte);
+}

src/libc/src/printf.c

@@ -0,0 +1,913 @@
+///////////////////////////////////////////////////////////////////////////////
+// \author (c) Marco Paland (info@paland.com)
+//             2014-2019, PALANDesign Hannover, Germany
+//
+// \license The MIT License (MIT)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+// \brief Tiny printf, sprintf and (v)snprintf implementation, optimized for speed on
+//        embedded systems with a very limited resources. These routines are thread
+//        safe and reentrant!
+//        Use this instead of the bloated standard/newlib printf cause these use
+//        malloc for printf (and may not be thread safe).
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+
+// define this globally (e.g. gcc -DPRINTF_INCLUDE_CONFIG_H ...) to include the
+// printf_config.h header file
+// default: undefined
+#ifdef PRINTF_INCLUDE_CONFIG_H
+#include "printf_config.h"
+#endif
+
+
+// 'ntoa' conversion buffer size, this must be big enough to hold one converted
+// numeric number including padded zeros (dynamically created on stack)
+// default: 32 byte
+#ifndef PRINTF_NTOA_BUFFER_SIZE
+#define PRINTF_NTOA_BUFFER_SIZE    32U
+#endif
+
+// 'ftoa' conversion buffer size, this must be big enough to hold one converted
+// float number including padded zeros (dynamically created on stack)
+// default: 32 byte
+#ifndef PRINTF_FTOA_BUFFER_SIZE
+#define PRINTF_FTOA_BUFFER_SIZE    32U
+#endif
+
+// support for the floating point type (%f)
+// default: activated
+#ifndef PRINTF_DISABLE_SUPPORT_FLOAT
+#define PRINTF_SUPPORT_FLOAT
+#endif
+
+// support for exponential floating point notation (%e/%g)
+// default: activated
+#ifndef PRINTF_DISABLE_SUPPORT_EXPONENTIAL
+#define PRINTF_SUPPORT_EXPONENTIAL
+#endif
+
+// define the default floating point precision
+// default: 6 digits
+#ifndef PRINTF_DEFAULT_FLOAT_PRECISION
+#define PRINTF_DEFAULT_FLOAT_PRECISION  6U
+#endif
+
+// define the largest float suitable to print with %f
+// default: 1e9
+#ifndef PRINTF_MAX_FLOAT
+#define PRINTF_MAX_FLOAT  1e9
+#endif
+
+// support for the long long types (%llu or %p)
+// default: activated
+#ifndef PRINTF_DISABLE_SUPPORT_LONG_LONG
+#define PRINTF_SUPPORT_LONG_LONG
+#endif
+
+// support for the ptrdiff_t type (%t)
+// ptrdiff_t is normally defined in <stddef.h> as long or long long type
+// default: activated
+#ifndef PRINTF_DISABLE_SUPPORT_PTRDIFF_T
+#define PRINTF_SUPPORT_PTRDIFF_T
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
+// internal flag definitions
+#define FLAGS_ZEROPAD   (1U <<  0U)
+#define FLAGS_LEFT      (1U <<  1U)
+#define FLAGS_PLUS      (1U <<  2U)
+#define FLAGS_SPACE     (1U <<  3U)
+#define FLAGS_HASH      (1U <<  4U)
+#define FLAGS_UPPERCASE (1U <<  5U)
+#define FLAGS_CHAR      (1U <<  6U)
+#define FLAGS_SHORT     (1U <<  7U)
+#define FLAGS_LONG      (1U <<  8U)
+#define FLAGS_LONG_LONG (1U <<  9U)
+#define FLAGS_PRECISION (1U << 10U)
+#define FLAGS_ADAPT_EXP (1U << 11U)
+
+
+// import float.h for DBL_MAX
+#if defined(PRINTF_SUPPORT_FLOAT)
+#include <float.h>
+#endif
+
+
+// output function type
+typedef void (*out_fct_type)(char character, void* buffer, size_t idx, size_t maxlen);
+
+
+// wrapper (used as buffer) for output function type
+typedef struct {
+  void  (*fct)(char character, void* arg);
+  void* arg;
+} out_fct_wrap_type;
+
+
+// internal buffer output
+static inline void _out_buffer(char character, void* buffer, size_t idx, size_t maxlen)
+{
+  if (idx < maxlen) {
+    ((char*)buffer)[idx] = character;
+  }
+}
+
+
+// internal null output
+static inline void _out_null(char character, void* buffer, size_t idx, size_t maxlen)
+{
+  (void)character; (void)buffer; (void)idx; (void)maxlen;
+}
+
+
+// internal _putchar wrapper
+static inline void _out_char(char character, void* buffer, size_t idx, size_t maxlen)
+{
+  (void)buffer; (void)idx; (void)maxlen;
+  if (character) {
+    _putchar(character);
+  }
+}
+
+
+// internal output function wrapper
+static inline void _out_fct(char character, void* buffer, size_t idx, size_t maxlen)
+{
+  (void)idx; (void)maxlen;
+  if (character) {
+    // buffer is the output fct pointer
+    ((out_fct_wrap_type*)buffer)->fct(character, ((out_fct_wrap_type*)buffer)->arg);
+  }
+}
+
+
+// internal secure strlen
+// \return The length of the string (excluding the terminating 0) limited by 'maxsize'
+static inline unsigned int _strnlen_s(const char* str, size_t maxsize)
+{
+  const char* s;
+  for (s = str; *s && maxsize--; ++s);
+  return (unsigned int)(s - str);
+}
+
+
+// internal test if char is a digit (0-9)
+// \return true if char is a digit
+static inline bool _is_digit(char ch)
+{
+  return (ch >= '0') && (ch <= '9');
+}
+
+
+// internal ASCII string to unsigned int conversion
+static unsigned int _atoi(const char** str)
+{
+  unsigned int i = 0U;
+  while (_is_digit(**str)) {
+    i = i * 10U + (unsigned int)(*((*str)++) - '0');
+  }
+  return i;
+}
+
+
+// output the specified string in reverse, taking care of any zero-padding
+static size_t _out_rev(out_fct_type out, char* buffer, size_t idx, size_t maxlen, const char* buf, size_t len, unsigned int width, unsigned int flags)
+{
+  const size_t start_idx = idx;
+
+  // pad spaces up to given width
+  if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) {
+    for (size_t i = len; i < width; i++) {
+      out(' ', buffer, idx++, maxlen);
+    }
+  }
+
+  // reverse string
+  while (len) {
+    out(buf[--len], buffer, idx++, maxlen);
+  }
+
+  // append pad spaces up to given width
+  if (flags & FLAGS_LEFT) {
+    while (idx - start_idx < width) {
+      out(' ', buffer, idx++, maxlen);
+    }
+  }
+
+  return idx;
+}
+
+
+// internal itoa format
+static size_t _ntoa_format(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, unsigned int base, unsigned int prec, unsigned int width, unsigned int flags)
+{
+  // pad leading zeros
+  if (!(flags & FLAGS_LEFT)) {
+    if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
+      width--;
+    }
+    while ((len < prec) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+      buf[len++] = '0';
+    }
+    while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+      buf[len++] = '0';
+    }
+  }
+
+  // handle hash
+  if (flags & FLAGS_HASH) {
+    if (!(flags & FLAGS_PRECISION) && len && ((len == prec) || (len == width))) {
+      len--;
+      if (len && (base == 16U)) {
+        len--;
+      }
+    }
+    if ((base == 16U) && !(flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+      buf[len++] = 'x';
+    }
+    else if ((base == 16U) && (flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+      buf[len++] = 'X';
+    }
+    else if ((base == 2U) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+      buf[len++] = 'b';
+    }
+    if (len < PRINTF_NTOA_BUFFER_SIZE) {
+      buf[len++] = '0';
+    }
+  }
+
+  if (len < PRINTF_NTOA_BUFFER_SIZE) {
+    if (negative) {
+      buf[len++] = '-';
+    }
+    else if (flags & FLAGS_PLUS) {
+      buf[len++] = '+';  // ignore the space if the '+' exists
+    }
+    else if (flags & FLAGS_SPACE) {
+      buf[len++] = ' ';
+    }
+  }
+
+  return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
+}
+
+
+// internal itoa for 'long' type
+static size_t _ntoa_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long value, bool negative, unsigned long base, unsigned int prec, unsigned int width, unsigned int flags)
+{
+  char buf[PRINTF_NTOA_BUFFER_SIZE];
+  size_t len = 0U;
+
+  // no hash for 0 values
+  if (!value) {
+    flags &= ~FLAGS_HASH;
+  }
+
+  // write if precision != 0 and value is != 0
+  if (!(flags & FLAGS_PRECISION) || value) {
+    do {
+      const char digit = (char)(value % base);
+      buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
+      value /= base;
+    } while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
+  }
+
+  return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
+}
+
+
+// internal itoa for 'long long' type
+#if defined(PRINTF_SUPPORT_LONG_LONG)
+static size_t _ntoa_long_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long long value, bool negative, unsigned long long base, unsigned int prec, unsigned int width, unsigned int flags)
+{
+  char buf[PRINTF_NTOA_BUFFER_SIZE];
+  size_t len = 0U;
+
+  // no hash for 0 values
+  if (!value) {
+    flags &= ~FLAGS_HASH;
+  }
+
+  // write if precision != 0 and value is != 0
+  if (!(flags & FLAGS_PRECISION) || value) {
+    do {
+      const char digit = (char)(value % base);
+      buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
+      value /= base;
+    } while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
+  }
+
+  return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
+}
+#endif  // PRINTF_SUPPORT_LONG_LONG
+
+
+#if defined(PRINTF_SUPPORT_FLOAT)
+
+#if defined(PRINTF_SUPPORT_EXPONENTIAL)
+// forward declaration so that _ftoa can switch to exp notation for values > PRINTF_MAX_FLOAT
+static size_t _etoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags);
+#endif
+
+
+// internal ftoa for fixed decimal floating point
+static size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
+{
+  char buf[PRINTF_FTOA_BUFFER_SIZE];
+  size_t len  = 0U;
+  double diff = 0.0;
+
+  // powers of 10
+  static const double pow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
+
+  // test for special values
+  if (value != value)
+    return _out_rev(out, buffer, idx, maxlen, "nan", 3, width, flags);
+  if (value < -DBL_MAX)
+    return _out_rev(out, buffer, idx, maxlen, "fni-", 4, width, flags);
+  if (value > DBL_MAX)
+    return _out_rev(out, buffer, idx, maxlen, (flags & FLAGS_PLUS) ? "fni+" : "fni", (flags & FLAGS_PLUS) ? 4U : 3U, width, flags);
+
+  // test for very large values
+  // standard printf behavior is to print EVERY whole number digit -- which could be 100s of characters overflowing your buffers == bad
+  if ((value > PRINTF_MAX_FLOAT) || (value < -PRINTF_MAX_FLOAT)) {
+#if defined(PRINTF_SUPPORT_EXPONENTIAL)
+    return _etoa(out, buffer, idx, maxlen, value, prec, width, flags);
+#else
+    return 0U;
+#endif
+  }
+
+  // test for negative
+  bool negative = false;
+  if (value < 0) {
+    negative = true;
+    value = 0 - value;
+  }
+
+  // set default precision, if not set explicitly
+  if (!(flags & FLAGS_PRECISION)) {
+    prec = PRINTF_DEFAULT_FLOAT_PRECISION;
+  }
+  // limit precision to 9, cause a prec >= 10 can lead to overflow errors
+  while ((len < PRINTF_FTOA_BUFFER_SIZE) && (prec > 9U)) {
+    buf[len++] = '0';
+    prec--;
+  }
+
+  int whole = (int)value;
+  double tmp = (value - whole) * pow10[prec];
+  unsigned long frac = (unsigned long)tmp;
+  diff = tmp - frac;
+
+  if (diff > 0.5) {
+    ++frac;
+    // handle rollover, e.g. case 0.99 with prec 1 is 1.0
+    if (frac >= pow10[prec]) {
+      frac = 0;
+      ++whole;
+    }
+  }
+  else if (diff < 0.5) {
+  }
+  else if ((frac == 0U) || (frac & 1U)) {
+    // if halfway, round up if odd OR if last digit is 0
+    ++frac;
+  }
+
+  if (prec == 0U) {
+    diff = value - (double)whole;
+    if ((!(diff < 0.5) || (diff > 0.5)) && (whole & 1)) {
+      // exactly 0.5 and ODD, then round up
+      // 1.5 -> 2, but 2.5 -> 2
+      ++whole;
+    }
+  }
+  else {
+    unsigned int count = prec;
+    // now do fractional part, as an unsigned number
+    while (len < PRINTF_FTOA_BUFFER_SIZE) {
+      --count;
+      buf[len++] = (char)(48U + (frac % 10U));
+      if (!(frac /= 10U)) {
+        break;
+      }
+    }
+    // add extra 0s
+    while ((len < PRINTF_FTOA_BUFFER_SIZE) && (count-- > 0U)) {
+      buf[len++] = '0';
+    }
+    if (len < PRINTF_FTOA_BUFFER_SIZE) {
+      // add decimal
+      buf[len++] = '.';
+    }
+  }
+
+  // do whole part, number is reversed
+  while (len < PRINTF_FTOA_BUFFER_SIZE) {
+    buf[len++] = (char)(48 + (whole % 10));
+    if (!(whole /= 10)) {
+      break;
+    }
+  }
+
+  // pad leading zeros
+  if (!(flags & FLAGS_LEFT) && (flags & FLAGS_ZEROPAD)) {
+    if (width && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
+      width--;
+    }
+    while ((len < width) && (len < PRINTF_FTOA_BUFFER_SIZE)) {
+      buf[len++] = '0';
+    }
+  }
+
+  if (len < PRINTF_FTOA_BUFFER_SIZE) {
+    if (negative) {
+      buf[len++] = '-';
+    }
+    else if (flags & FLAGS_PLUS) {
+      buf[len++] = '+';  // ignore the space if the '+' exists
+    }
+    else if (flags & FLAGS_SPACE) {
+      buf[len++] = ' ';
+    }
+  }
+
+  return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
+}
+
+
+#if defined(PRINTF_SUPPORT_EXPONENTIAL)
+// internal ftoa variant for exponential floating-point type, contributed by Martijn Jasperse <m.jasperse@gmail.com>
+static size_t _etoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
+{
+  // check for NaN and special values
+  if ((value != value) || (value > DBL_MAX) || (value < -DBL_MAX)) {
+    return _ftoa(out, buffer, idx, maxlen, value, prec, width, flags);
+  }
+
+  // determine the sign
+  const bool negative = value < 0;
+  if (negative) {
+    value = -value;
+  }
+
+  // default precision
+  if (!(flags & FLAGS_PRECISION)) {
+    prec = PRINTF_DEFAULT_FLOAT_PRECISION;
+  }
+
+  // determine the decimal exponent
+  // based on the algorithm by David Gay (https://www.ampl.com/netlib/fp/dtoa.c)
+  union {
+    uint64_t U;
+    double   F;
+  } conv;
+
+  conv.F = value;
+  int exp2 = (int)((conv.U >> 52U) & 0x07FFU) - 1023;           // effectively log2
+  conv.U = (conv.U & ((1ULL << 52U) - 1U)) | (1023ULL << 52U);  // drop the exponent so conv.F is now in [1,2)
+  // now approximate log10 from the log2 integer part and an expansion of ln around 1.5
+  int expval = (int)(0.1760912590558 + exp2 * 0.301029995663981 + (conv.F - 1.5) * 0.289529654602168);
+  // now we want to compute 10^expval but we want to be sure it won't overflow
+  exp2 = (int)(expval * 3.321928094887362 + 0.5);
+  const double z  = expval * 2.302585092994046 - exp2 * 0.6931471805599453;
+  const double z2 = z * z;
+  conv.U = (uint64_t)(exp2 + 1023) << 52U;
+  // compute exp(z) using continued fractions, see https://en.wikipedia.org/wiki/Exponential_function#Continued_fractions_for_ex
+  conv.F *= 1 + 2 * z / (2 - z + (z2 / (6 + (z2 / (10 + z2 / 14)))));
+  // correct for rounding errors
+  if (value < conv.F) {
+    expval--;
+    conv.F /= 10;
+  }
+
+  // the exponent format is "%+03d" and largest value is "307", so set aside 4-5 characters
+  unsigned int minwidth = ((expval < 100) && (expval > -100)) ? 4U : 5U;
+
+  // in "%g" mode, "prec" is the number of *significant figures* not decimals
+  if (flags & FLAGS_ADAPT_EXP) {
+    // do we want to fall-back to "%f" mode?
+    if ((value >= 1e-4) && (value < 1e6)) {
+      if ((int)prec > expval) {
+        prec = (unsigned)((int)prec - expval - 1);
+      }
+      else {
+        prec = 0;
+      }
+      flags |= FLAGS_PRECISION;   // make sure _ftoa respects precision
+      // no characters in exponent
+      minwidth = 0U;
+      expval   = 0;
+    }
+    else {
+      // we use one sigfig for the whole part
+      if ((prec > 0) && (flags & FLAGS_PRECISION)) {
+        --prec;
+      }
+    }
+  }
+
+  // will everything fit?
+  unsigned int fwidth = width;
+  if (width > minwidth) {
+    // we didn't fall-back so subtract the characters required for the exponent
+    fwidth -= minwidth;
+  } else {
+    // not enough characters, so go back to default sizing
+    fwidth = 0U;
+  }
+  if ((flags & FLAGS_LEFT) && minwidth) {
+    // if we're padding on the right, DON'T pad the floating part
+    fwidth = 0U;
+  }
+
+  // rescale the float value
+  if (expval) {
+    value /= conv.F;
+  }
+
+  // output the floating part
+  const size_t start_idx = idx;
+  idx = _ftoa(out, buffer, idx, maxlen, negative ? -value : value, prec, fwidth, flags & ~FLAGS_ADAPT_EXP);
+
+  // output the exponent part
+  if (minwidth) {
+    // output the exponential symbol
+    out((flags & FLAGS_UPPERCASE) ? 'E' : 'e', buffer, idx++, maxlen);
+    // output the exponent value
+    idx = _ntoa_long(out, buffer, idx, maxlen, (expval < 0) ? -expval : expval, expval < 0, 10, 0, minwidth-1, FLAGS_ZEROPAD | FLAGS_PLUS);
+    // might need to right-pad spaces
+    if (flags & FLAGS_LEFT) {
+      while (idx - start_idx < width) out(' ', buffer, idx++, maxlen);
+    }
+  }
+  return idx;
+}
+#endif  // PRINTF_SUPPORT_EXPONENTIAL
+#endif  // PRINTF_SUPPORT_FLOAT
+
+
+// internal vsnprintf
+static int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const char* format, va_list va)
+{
+  unsigned int flags, width, precision, n;
+  size_t idx = 0U;
+
+  if (!buffer) {
+    // use null output function
+    out = _out_null;
+  }
+
+  while (*format)
+  {
+    // format specifier?  %[flags][width][.precision][length]
+    if (*format != '%') {
+      // no
+      out(*format, buffer, idx++, maxlen);
+      format++;
+      continue;
+    }
+    else {
+      // yes, evaluate it
+      format++;
+    }
+
+    // evaluate flags
+    flags = 0U;
+    do {
+      switch (*format) {
+        case '0': flags |= FLAGS_ZEROPAD; format++; n = 1U; break;
+        case '-': flags |= FLAGS_LEFT;    format++; n = 1U; break;
+        case '+': flags |= FLAGS_PLUS;    format++; n = 1U; break;
+        case ' ': flags |= FLAGS_SPACE;   format++; n = 1U; break;
+        case '#': flags |= FLAGS_HASH;    format++; n = 1U; break;
+        default :                                   n = 0U; break;
+      }
+    } while (n);
+
+    // evaluate width field
+    width = 0U;
+    if (_is_digit(*format)) {
+      width = _atoi(&format);
+    }
+    else if (*format == '*') {
+      const int w = va_arg(va, int);
+      if (w < 0) {
+        flags |= FLAGS_LEFT;    // reverse padding
+        width = (unsigned int)-w;
+      }
+      else {
+        width = (unsigned int)w;
+      }
+      format++;
+    }
+
+    // evaluate precision field
+    precision = 0U;
+    if (*format == '.') {
+      flags |= FLAGS_PRECISION;
+      format++;
+      if (_is_digit(*format)) {
+        precision = _atoi(&format);
+      }
+      else if (*format == '*') {
+        const int prec = (int)va_arg(va, int);
+        precision = prec > 0 ? (unsigned int)prec : 0U;
+        format++;
+      }
+    }
+
+    // evaluate length field
+    switch (*format) {
+      case 'l' :
+        flags |= FLAGS_LONG;
+        format++;
+        if (*format == 'l') {
+          flags |= FLAGS_LONG_LONG;
+          format++;
+        }
+        break;
+      case 'h' :
+        flags |= FLAGS_SHORT;
+        format++;
+        if (*format == 'h') {
+          flags |= FLAGS_CHAR;
+          format++;
+        }
+        break;
+#if defined(PRINTF_SUPPORT_PTRDIFF_T)
+      case 't' :
+        flags |= (sizeof(ptrdiff_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
+        format++;
+        break;
+#endif
+      case 'j' :
+        flags |= (sizeof(intmax_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
+        format++;
+        break;
+      case 'z' :
+        flags |= (sizeof(size_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
+        format++;
+        break;
+      default :
+        break;
+    }
+
+    // evaluate specifier
+    switch (*format) {
+      case 'd' :
+      case 'i' :
+      case 'u' :
+      case 'x' :
+      case 'X' :
+      case 'o' :
+      case 'b' : {
+        // set the base
+        unsigned int base;
+        if (*format == 'x' || *format == 'X') {
+          base = 16U;
+        }
+        else if (*format == 'o') {
+          base =  8U;
+        }
+        else if (*format == 'b') {
+          base =  2U;
+        }
+        else {
+          base = 10U;
+          flags &= ~FLAGS_HASH;   // no hash for dec format
+        }
+        // uppercase
+        if (*format == 'X') {
+          flags |= FLAGS_UPPERCASE;
+        }
+
+        // no plus or space flag for u, x, X, o, b
+        if ((*format != 'i') && (*format != 'd')) {
+          flags &= ~(FLAGS_PLUS | FLAGS_SPACE);
+        }
+
+        // ignore '0' flag when precision is given
+        if (flags & FLAGS_PRECISION) {
+          flags &= ~FLAGS_ZEROPAD;
+        }
+
+        // convert the integer
+        if ((*format == 'i') || (*format == 'd')) {
+          // signed
+          if (flags & FLAGS_LONG_LONG) {
+#if defined(PRINTF_SUPPORT_LONG_LONG)
+            const long long value = va_arg(va, long long);
+            idx = _ntoa_long_long(out, buffer, idx, maxlen, (unsigned long long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
+#endif
+          }
+          else if (flags & FLAGS_LONG) {
+            const long value = va_arg(va, long);
+            idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
+          }
+          else {
+            const int value = (flags & FLAGS_CHAR) ? (char)va_arg(va, int) : (flags & FLAGS_SHORT) ? (short int)va_arg(va, int) : va_arg(va, int);
+            idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned int)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
+          }
+        }
+        else {
+          // unsigned
+          if (flags & FLAGS_LONG_LONG) {
+#if defined(PRINTF_SUPPORT_LONG_LONG)
+            idx = _ntoa_long_long(out, buffer, idx, maxlen, va_arg(va, unsigned long long), false, base, precision, width, flags);
+#endif
+          }
+          else if (flags & FLAGS_LONG) {
+            idx = _ntoa_long(out, buffer, idx, maxlen, va_arg(va, unsigned long), false, base, precision, width, flags);
+          }
+          else {
+            const unsigned int value = (flags & FLAGS_CHAR) ? (unsigned char)va_arg(va, unsigned int) : (flags & FLAGS_SHORT) ? (unsigned short int)va_arg(va, unsigned int) : va_arg(va, unsigned int);
+            idx = _ntoa_long(out, buffer, idx, maxlen, value, false, base, precision, width, flags);
+          }
+        }
+        format++;
+        break;
+      }
+#if defined(PRINTF_SUPPORT_FLOAT)
+      case 'f' :
+      case 'F' :
+        if (*format == 'F') flags |= FLAGS_UPPERCASE;
+        idx = _ftoa(out, buffer, idx, maxlen, va_arg(va, double), precision, width, flags);
+        format++;
+        break;
+#if defined(PRINTF_SUPPORT_EXPONENTIAL)
+      case 'e':
+      case 'E':
+      case 'g':
+      case 'G':
+        if ((*format == 'g')||(*format == 'G')) flags |= FLAGS_ADAPT_EXP;
+        if ((*format == 'E')||(*format == 'G')) flags |= FLAGS_UPPERCASE;
+        idx = _etoa(out, buffer, idx, maxlen, va_arg(va, double), precision, width, flags);
+        format++;
+        break;
+#endif  // PRINTF_SUPPORT_EXPONENTIAL
+#endif  // PRINTF_SUPPORT_FLOAT
+      case 'c' : {
+        unsigned int l = 1U;
+        // pre padding
+        if (!(flags & FLAGS_LEFT)) {
+          while (l++ < width) {
+            out(' ', buffer, idx++, maxlen);
+          }
+        }
+        // char output
+        out((char)va_arg(va, int), buffer, idx++, maxlen);
+        // post padding
+        if (flags & FLAGS_LEFT) {
+          while (l++ < width) {
+            out(' ', buffer, idx++, maxlen);
+          }
+        }
+        format++;
+        break;
+      }
+
+      case 's' : {
+        const char* p = va_arg(va, char*);
+        unsigned int l = _strnlen_s(p, precision ? precision : (size_t)-1);
+        // pre padding
+        if (flags & FLAGS_PRECISION) {
+          l = (l < precision ? l : precision);
+        }
+        if (!(flags & FLAGS_LEFT)) {
+          while (l++ < width) {
+            out(' ', buffer, idx++, maxlen);
+          }
+        }
+        // string output
+        while ((*p != 0) && (!(flags & FLAGS_PRECISION) || precision--)) {
+          out(*(p++), buffer, idx++, maxlen);
+        }
+        // post padding
+        if (flags & FLAGS_LEFT) {
+          while (l++ < width) {
+            out(' ', buffer, idx++, maxlen);
+          }
+        }
+        format++;
+        break;
+      }
+
+      case 'p' : {
+        width = sizeof(void*) * 2U;
+        flags |= FLAGS_ZEROPAD | FLAGS_UPPERCASE;
+#if defined(PRINTF_SUPPORT_LONG_LONG)
+        const bool is_ll = sizeof(uintptr_t) == sizeof(long long);
+        if (is_ll) {
+          idx = _ntoa_long_long(out, buffer, idx, maxlen, (uintptr_t)va_arg(va, void*), false, 16U, precision, width, flags);
+        }
+        else {
+#endif
+          idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)((uintptr_t)va_arg(va, void*)), false, 16U, precision, width, flags);
+#if defined(PRINTF_SUPPORT_LONG_LONG)
+        }
+#endif
+        format++;
+        break;
+      }
+
+      case '%' :
+        out('%', buffer, idx++, maxlen);
+        format++;
+        break;
+
+      default :
+        out(*format, buffer, idx++, maxlen);
+        format++;
+        break;
+    }
+  }
+
+  // termination
+  out((char)0, buffer, idx < maxlen ? idx : maxlen - 1U, maxlen);
+
+  // return written chars without terminating \0
+  return (int)idx;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+int printf_(const char* format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  char buffer[1];
+  const int ret = _vsnprintf(_out_char, buffer, (size_t)-1, format, va);
+  va_end(va);
+  _putchar('\n');
+  return ret;
+}
+
+
+int sprintf_(char* buffer, const char* format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  const int ret = _vsnprintf(_out_buffer, buffer, (size_t)-1, format, va);
+  va_end(va);
+  return ret;
+}
+
+
+int snprintf_(char* buffer, size_t count, const char* format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  const int ret = _vsnprintf(_out_buffer, buffer, count, format, va);
+  va_end(va);
+  return ret;
+}
+
+
+int vprintf_(const char* format, va_list va)
+{
+  char buffer[1];
+  return _vsnprintf(_out_char, buffer, (size_t)-1, format, va);
+}
+
+
+int vsnprintf_(char* buffer, size_t count, const char* format, va_list va)
+{
+  return _vsnprintf(_out_buffer, buffer, count, format, va);
+}
+
+
+int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  const out_fct_wrap_type out_fct_wrap = { out, arg };
+  const int ret = _vsnprintf(_out_fct, (char*)(uintptr_t)&out_fct_wrap, (size_t)-1, format, va);
+  va_end(va);
+  return ret;
+}

src/libunwind/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+authors = ["The Rust Project Developers"]
+name = "unwind"
+version = "0.0.0"
+build = "build.rs"
+edition = "2018"
+include = [
+  '/libunwind/*',
+]
+
+[lib]
+name = "unwind"
+path = "lib.rs"
+test = false
+bench = false
+doc = false
+
+[dependencies]
+compiler_builtins = "0.1.0"
+cfg-if = "0.1.8"
+libc = { path = "../libc" }
+
+[build-dependencies]
+cc = { version = "1.0.1" }
+
+[features]
+llvm-libunwind = []

src/libunwind/backtrace.rs

@@ -0,0 +1,41 @@
+use libc::{c_void, c_int};
+use crate::libunwind as uw;
+
+const UW_REG_SP: c_int = 13;
+
+pub fn backtrace<F>(f: F) -> Result<(), uw::_Unwind_Reason_Code>
+    where F: FnMut(usize) -> ()
+{
+    struct TraceContext<F> {
+        step_fn: F,
+        prev_sp: uw::_Unwind_Word
+    }
+
+    extern fn trace<F>(context: *mut uw::_Unwind_Context, arg: *mut c_void)
+                      -> uw::_Unwind_Reason_Code
+        where F: FnMut(usize) -> ()
+    {
+        unsafe {
+            let trace_context = &mut *(arg as *mut TraceContext<F>);
+
+            // Detect the root of a libfringe thread
+            let cur_sp = uw::_Unwind_GetGR(context, UW_REG_SP);
+            if cur_sp == trace_context.prev_sp {
+                return uw::_URC_END_OF_STACK
+            } else {
+                trace_context.prev_sp = cur_sp;
+            }
+
+            (trace_context.step_fn)(uw::_Unwind_GetIP(context));
+            uw::_URC_NO_REASON
+        }
+    }
+
+    unsafe {
+        let mut trace_context = TraceContext { step_fn: f, prev_sp: 0 };
+        match uw::_Unwind_Backtrace(trace::<F>, &mut trace_context as *mut _ as *mut c_void) {
+            uw::_URC_NO_REASON => Ok(()),
+            err => Err(err)
+        }
+    }
+}

src/libunwind/build.rs

@@ -0,0 +1,64 @@
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    llvm_libunwind::compile();
+}
+
+mod llvm_libunwind {
+    use std::path::Path;
+
+    /// Compile the libunwind C/C++ source code.
+    pub fn compile() {
+        let cfg = &mut cc::Build::new();
+        cfg.cpp(true);
+        cfg.cpp_set_stdlib(None);
+        cfg.warnings(false);
+
+        // libunwind expects a __LITTLE_ENDIAN__ macro to be set for LE archs, cf. #65765
+        cfg.define("__LITTLE_ENDIAN__", Some("1"));
+        // still have problem compiling the libunwind
+        cfg.flag("-nostdlib");
+        cfg.flag("-ffreestanding");
+        cfg.flag("-fno-PIC");
+        cfg.flag("-Isrc");
+        cfg.flag("-isystem../include");
+        cfg.flag("-fno-stack-protector");
+        cfg.flag("--target=armv7-none-eabihf");
+        cfg.define("_LIBUNWIND_IS_BAREMETAL", Some("1"));
+        cfg.define("_LIBUNWIND_NO_HEAP", Some("1"));
+        cfg.define("_LIBUNWIND_HAS_NO_THREADS", Some("1"));
+        cfg.define("NDEBUG", Some("1"));
+
+        cfg.flag("-std=c99");
+        cfg.flag("-std=c++11");
+        cfg.flag("-nostdinc++");
+        cfg.flag("-fno-exceptions");
+        cfg.flag("-fno-rtti");
+        cfg.flag("-fstrict-aliasing");
+        cfg.flag("-funwind-tables");
+        cfg.flag("-fvisibility=hidden");
+        cfg.flag_if_supported("-fvisibility-global-new-delete-hidden");
+        cfg.define("_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS", None);
+        cfg.flag("-U_FORTIFY_SOURCE");
+        cfg.define("_FORTIFY_SOURCE", Some("0"));
+
+        let unwind_sources = vec![
+            "Unwind-EHABI.cpp",
+            "Unwind-seh.cpp",
+            "Unwind-sjlj.c",
+            "UnwindLevel1-gcc-ext.c",
+            "UnwindLevel1.c",
+            "UnwindRegistersRestore.S",
+            "UnwindRegistersSave.S",
+            "libunwind.cpp"
+        ];
+
+        let root = Path::new("../llvm_libunwind");
+        cfg.include(root.join("include"));
+        for src in unwind_sources {
+            println!("cargo:rerun-if-changed={}", src);
+            cfg.file(root.join("src").join(src));
+        }
+
+        cfg.compile("unwind");
+    }
+}

src/libunwind/lib.rs

@@ -0,0 +1,33 @@
+#![no_std]
+#![feature(link_cfg)]
+#![feature(nll)]
+#![feature(unwind_attributes)]
+#![feature(static_nobundle)]
+#![cfg_attr(not(target_env = "msvc"), feature(libc))]
+
+cfg_if::cfg_if! {
+    if #[cfg(target_env = "msvc")] {
+        // no extra unwinder support needed
+    } else if #[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))] {
+        // no unwinder on the system!
+    } else {
+        mod libunwind;
+        pub use libunwind::*;
+        mod backtrace;
+        pub use backtrace::backtrace;
+    }
+}
+
+#[cfg(target_env = "musl")]
+#[link(name = "unwind", kind = "static", cfg(target_feature = "crt-static"))]
+#[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
+extern "C" {}
+
+#[cfg(target_os = "redox")]
+#[link(name = "gcc_eh", kind = "static-nobundle", cfg(target_feature = "crt-static"))]
+#[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
+extern "C" {}
+
+#[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
+#[link(name = "unwind", kind = "static-nobundle")]
+extern "C" {}

src/libunwind/libunwind.rs

@@ -0,0 +1,285 @@
+#![allow(nonstandard_style)]
+
+use libc::{c_int, c_void, uintptr_t};
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum _Unwind_Reason_Code {
+    _URC_NO_REASON = 0,
+    _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
+    _URC_FATAL_PHASE2_ERROR = 2,
+    _URC_FATAL_PHASE1_ERROR = 3,
+    _URC_NORMAL_STOP = 4,
+    _URC_END_OF_STACK = 5,
+    _URC_HANDLER_FOUND = 6,
+    _URC_INSTALL_CONTEXT = 7,
+    _URC_CONTINUE_UNWIND = 8,
+    _URC_FAILURE = 9, // used only by ARM EHABI
+}
+pub use _Unwind_Reason_Code::*;
+
+pub type _Unwind_Exception_Class = u64;
+pub type _Unwind_Word = uintptr_t;
+pub type _Unwind_Ptr = uintptr_t;
+pub type _Unwind_Trace_Fn =
+    extern "C" fn(ctx: *mut _Unwind_Context, arg: *mut c_void) -> _Unwind_Reason_Code;
+
+#[cfg(target_arch = "x86")]
+pub const unwinder_private_data_size: usize = 5;
+
+#[cfg(target_arch = "x86_64")]
+pub const unwinder_private_data_size: usize = 6;
+
+#[cfg(all(target_arch = "arm", not(target_os = "ios")))]
+pub const unwinder_private_data_size: usize = 20;
+
+#[cfg(all(target_arch = "arm", target_os = "ios"))]
+pub const unwinder_private_data_size: usize = 5;
+
+#[cfg(target_arch = "aarch64")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_arch = "mips")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_arch = "mips64")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_arch = "s390x")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_arch = "sparc64")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_arch = "riscv64")]
+pub const unwinder_private_data_size: usize = 2;
+
+#[cfg(target_os = "emscripten")]
+pub const unwinder_private_data_size: usize = 20;
+
+#[cfg(all(target_arch = "hexagon", target_os = "linux"))]
+pub const unwinder_private_data_size: usize = 35;
+
+#[repr(C)]
+pub struct _Unwind_Exception {
+    pub exception_class: _Unwind_Exception_Class,
+    pub exception_cleanup: _Unwind_Exception_Cleanup_Fn,
+    pub private: [_Unwind_Word; unwinder_private_data_size],
+}
+
+pub enum _Unwind_Context {}
+
+pub type _Unwind_Exception_Cleanup_Fn =
+    extern "C" fn(unwind_code: _Unwind_Reason_Code, exception: *mut _Unwind_Exception);
+#[cfg_attr(
+    all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux")),
+    link(name = "unwind", kind = "static")
+)]
+extern "C" {
+    #[unwind(allowed)]
+    pub fn _Unwind_Resume(exception: *mut _Unwind_Exception) -> !;
+    pub fn _Unwind_DeleteException(exception: *mut _Unwind_Exception);
+    pub fn _Unwind_GetLanguageSpecificData(ctx: *mut _Unwind_Context) -> *mut c_void;
+    pub fn _Unwind_GetRegionStart(ctx: *mut _Unwind_Context) -> _Unwind_Ptr;
+    pub fn _Unwind_GetTextRelBase(ctx: *mut _Unwind_Context) -> _Unwind_Ptr;
+    pub fn _Unwind_GetDataRelBase(ctx: *mut _Unwind_Context) -> _Unwind_Ptr;
+}
+
+cfg_if::cfg_if! {
+if #[cfg(all(any(target_os = "ios", target_os = "netbsd", not(target_arch = "arm"))))] {
+    // Not ARM EHABI
+    #[repr(C)]
+    #[derive(Copy, Clone, PartialEq)]
+    pub enum _Unwind_Action {
+        _UA_SEARCH_PHASE = 1,
+        _UA_CLEANUP_PHASE = 2,
+        _UA_HANDLER_FRAME = 4,
+        _UA_FORCE_UNWIND = 8,
+        _UA_END_OF_STACK = 16,
+    }
+    pub use _Unwind_Action::*;
+
+    #[cfg_attr(all(feature = "llvm-libunwind",
+                   any(target_os = "fuchsia", target_os = "linux")),
+               link(name = "unwind", kind = "static"))]
+    extern "C" {
+        pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word;
+        pub fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word);
+        pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> _Unwind_Word;
+        pub fn _Unwind_SetIP(ctx: *mut _Unwind_Context, value: _Unwind_Word);
+        pub fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context, ip_before_insn: *mut c_int)
+                                 -> _Unwind_Word;
+        pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;
+    }
+
+} else {
+    // ARM EHABI
+    #[repr(C)]
+    #[derive(Copy, Clone, PartialEq)]
+    pub enum _Unwind_State {
+        _US_VIRTUAL_UNWIND_FRAME = 0,
+        _US_UNWIND_FRAME_STARTING = 1,
+        _US_UNWIND_FRAME_RESUME = 2,
+        _US_ACTION_MASK = 3,
+        _US_FORCE_UNWIND = 8,
+        _US_END_OF_STACK = 16,
+    }
+    pub use _Unwind_State::*;
+
+    #[repr(C)]
+    enum _Unwind_VRS_Result {
+        _UVRSR_OK = 0,
+        _UVRSR_NOT_IMPLEMENTED = 1,
+        _UVRSR_FAILED = 2,
+    }
+    #[repr(C)]
+    enum _Unwind_VRS_RegClass {
+        _UVRSC_CORE = 0,
+        _UVRSC_VFP = 1,
+        _UVRSC_FPA = 2,
+        _UVRSC_WMMXD = 3,
+        _UVRSC_WMMXC = 4,
+    }
+    use _Unwind_VRS_RegClass::*;
+    #[repr(C)]
+    enum _Unwind_VRS_DataRepresentation {
+        _UVRSD_UINT32 = 0,
+        _UVRSD_VFPX = 1,
+        _UVRSD_FPAX = 2,
+        _UVRSD_UINT64 = 3,
+        _UVRSD_FLOAT = 4,
+        _UVRSD_DOUBLE = 5,
+    }
+    use _Unwind_VRS_DataRepresentation::*;
+
+    pub const UNWIND_POINTER_REG: c_int = 12;
+    pub const UNWIND_SP_REG: c_int = 13;
+    pub const UNWIND_IP_REG: c_int = 15;
+
+    #[cfg_attr(all(feature = "llvm-libunwind",
+                   any(target_os = "fuchsia", target_os = "linux")),
+               link(name = "unwind", kind = "static"))]
+    extern "C" {
+        fn _Unwind_VRS_Get(ctx: *mut _Unwind_Context,
+                           regclass: _Unwind_VRS_RegClass,
+                           regno: _Unwind_Word,
+                           repr: _Unwind_VRS_DataRepresentation,
+                           data: *mut c_void)
+                           -> _Unwind_VRS_Result;
+
+        fn _Unwind_VRS_Set(ctx: *mut _Unwind_Context,
+                           regclass: _Unwind_VRS_RegClass,
+                           regno: _Unwind_Word,
+                           repr: _Unwind_VRS_DataRepresentation,
+                           data: *mut c_void)
+                           -> _Unwind_VRS_Result;
+    }
+
+    // On Android or ARM/Linux, these are implemented as macros:
+
+    pub unsafe fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word {
+        let mut val: _Unwind_Word = 0;
+        _Unwind_VRS_Get(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
+                        &mut val as *mut _ as *mut c_void);
+        val
+    }
+
+    pub unsafe fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word) {
+        let mut value = value;
+        _Unwind_VRS_Set(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
+                        &mut value as *mut _ as *mut c_void);
+    }
+
+    pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context)
+                                -> _Unwind_Word {
+        let val = _Unwind_GetGR(ctx, UNWIND_IP_REG);
+        (val & !1) as _Unwind_Word
+    }
+
+    pub unsafe fn _Unwind_SetIP(ctx: *mut _Unwind_Context,
+                                value: _Unwind_Word) {
+        // Propagate thumb bit to instruction pointer
+        let thumb_state = _Unwind_GetGR(ctx, UNWIND_IP_REG) & 1;
+        let value = value | thumb_state;
+        _Unwind_SetGR(ctx, UNWIND_IP_REG, value);
+    }
+
+    pub unsafe fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context,
+                                    ip_before_insn: *mut c_int)
+                                    -> _Unwind_Word {
+        *ip_before_insn = 0;
+        _Unwind_GetIP(ctx)
+    }
+
+    // This function also doesn't exist on Android or ARM/Linux, so make it a no-op
+    pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void {
+        pc
+    }
+}
+} // cfg_if!
+
+cfg_if::cfg_if! {
+if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
+    // Not 32-bit iOS
+    #[cfg_attr(all(feature = "llvm-libunwind",
+                   any(target_os = "fuchsia", target_os = "linux")),
+               link(name = "unwind", kind = "static"))]
+    extern "C" {
+        #[unwind(allowed)]
+        pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
+        pub fn _Unwind_Backtrace(trace: _Unwind_Trace_Fn,
+                                 trace_argument: *mut c_void)
+                                 -> _Unwind_Reason_Code;
+    }
+} else {
+    // 32-bit iOS uses SjLj and does not provide _Unwind_Backtrace()
+    #[cfg_attr(all(feature = "llvm-libunwind",
+                   any(target_os = "fuchsia", target_os = "linux")),
+               link(name = "unwind", kind = "static"))]
+    extern "C" {
+        #[unwind(allowed)]
+        pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
+    }
+
+    #[inline]
+    pub unsafe fn _Unwind_RaiseException(exc: *mut _Unwind_Exception) -> _Unwind_Reason_Code {
+        _Unwind_SjLj_RaiseException(exc)
+    }
+}
+} // cfg_if!
+
+cfg_if::cfg_if! {
+if #[cfg(all(windows, target_arch = "x86_64", target_env = "gnu"))] {
+    // We declare these as opaque types. This is fine since you just need to
+    // pass them to _GCC_specific_handler and forget about them.
+    pub enum EXCEPTION_RECORD {}
+    pub type LPVOID = *mut c_void;
+    pub enum CONTEXT {}
+    pub enum DISPATCHER_CONTEXT {}
+    pub type EXCEPTION_DISPOSITION = c_int;
+    type PersonalityFn = unsafe extern "C" fn(version: c_int,
+                                              actions: _Unwind_Action,
+                                              exception_class: _Unwind_Exception_Class,
+                                              exception_object: *mut _Unwind_Exception,
+                                              context: *mut _Unwind_Context)
+                                              -> _Unwind_Reason_Code;
+
+    extern "C" {
+        pub fn _GCC_specific_handler(exceptionRecord: *mut EXCEPTION_RECORD,
+                                establisherFrame: LPVOID,
+                                contextRecord: *mut CONTEXT,
+                                dispatcherContext: *mut DISPATCHER_CONTEXT,
+                                personality: PersonalityFn)
+                                -> EXCEPTION_DISPOSITION;
+    }
+}
+} // cfg_if!
+
+#[no_mangle]
+extern fn abort() {
+    panic!("Abort!");
+}
+

src/runtime/Cargo.toml

@@ -24,4 +24,6 @@ libsupport_zynq = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
 libcortex_a9 = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
 libasync = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
 dyld = { path = "../libdyld" }
+unwind = { path = "../libunwind" }
+libc = { path = "../libc" }
 fatfs = { version = "0.3", features = ["core_io"], default-features = false }