From 7f983a453d06dc46efa348f94f42b1682abcf278 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sat, 25 Jul 2020 17:04:40 +0800
Subject: [PATCH] implement core device cache

---
 examples/device_db.py           |  5 +++
 src/runtime/src/kernel/api.rs   |  5 +++
 src/runtime/src/kernel/cache.rs | 79 +++++++++++++++++++++++++++++++++
 src/runtime/src/kernel/core1.rs |  4 ++
 src/runtime/src/kernel/mod.rs   |  1 +
 5 files changed, 94 insertions(+)
 create mode 100644 src/runtime/src/kernel/cache.rs

diff --git a/examples/device_db.py b/examples/device_db.py
index 9110390..105d50f 100644
--- a/examples/device_db.py
+++ b/examples/device_db.py
@@ -12,6 +12,11 @@ device_db = {
             "target": "cortexa9"
         }
     },
+    "core_cache": {
+        "type": "local",
+        "module": "artiq.coredevice.cache",
+        "class": "CoreCache"
+    },
     "core_dma": {
         "type": "local",
         "module": "artiq.coredevice.dma",
diff --git a/src/runtime/src/kernel/api.rs b/src/runtime/src/kernel/api.rs
index ae68fc5..f798d84 100644
--- a/src/runtime/src/kernel/api.rs
+++ b/src/runtime/src/kernel/api.rs
@@ -4,6 +4,7 @@ use crate::eh_artiq;
 use crate::rtio;
 use super::rpc::{rpc_send, rpc_send_async, rpc_recv};
 use super::dma;
+use super::cache;
 
 macro_rules! api {
     ($i:ident) => ({
@@ -58,6 +59,10 @@ pub fn resolve(required: &[u8]) -> Option<u32> {
         api!(dma_retrieve = dma::dma_retrieve),
         api!(dma_playback = dma::dma_playback),
 
+        // cache
+        api!(cache_get = cache::get),
+        api!(cache_put = cache::put),
+
         // Double-precision floating-point arithmetic helper functions
         // RTABI chapter 4.1.2, Table 2
         api!(__aeabi_dadd),
diff --git a/src/runtime/src/kernel/cache.rs b/src/runtime/src/kernel/cache.rs
new file mode 100644
index 0000000..1d2b1c5
--- /dev/null
+++ b/src/runtime/src/kernel/cache.rs
@@ -0,0 +1,79 @@
+use alloc::{string::String, vec::Vec, collections::BTreeMap};
+use libcortex_a9::mutex::Mutex;
+use cslice::{CSlice, AsCSlice};
+use core::mem::transmute;
+use core::str;
+use log::debug;
+
+use crate::artiq_raise;
+
+
+#[derive(Debug)]
+struct Entry {
+    data: Vec<i32>,
+    borrowed: bool
+}
+
+#[derive(Debug)]
+struct Cache {
+    entries: BTreeMap<String, Entry>
+}
+
+impl Cache {
+    pub const fn new() -> Cache {
+        Cache { entries: BTreeMap::new() }
+    }
+
+    pub fn get(&mut self, key: &str) -> *const [i32] {
+        match self.entries.get_mut(key) {
+            None => &[],
+            Some(ref mut entry) => {
+                entry.borrowed = true;
+                &entry.data[..]
+            }
+        }
+    }
+
+    pub fn put(&mut self, key: &str, data: &[i32]) -> Result<(), ()> {
+        match self.entries.get_mut(key) {
+            None => (),
+            Some(ref mut entry) => {
+                if entry.borrowed { return Err(()) }
+                entry.data = Vec::from(data);
+                return Ok(())
+            }
+        }
+
+        self.entries.insert(String::from(key), Entry {
+            data: Vec::from(data),
+            borrowed: false
+        });
+        Ok(())
+    }
+
+    pub unsafe fn unborrow(&mut self) {
+        for (_key, entry) in self.entries.iter_mut() {
+            entry.borrowed = false;
+        }
+    }
+}
+
+static CACHE: Mutex<Cache> = Mutex::new(Cache::new());
+
+pub extern fn get(key: CSlice<u8>) -> CSlice<'static, i32> {
+    let value = CACHE.lock().get(str::from_utf8(key.as_ref()).unwrap());
+    unsafe {
+        transmute::<*const [i32], &'static [i32]>(value).as_c_slice()
+    }
+}
+
+pub extern fn put(key: CSlice<u8>, list: CSlice<i32>) {
+    let result = CACHE.lock().put(str::from_utf8(key.as_ref()).unwrap(), list.as_ref());
+    if result.is_err() {
+        artiq_raise!("CacheError", "cannot put into a busy cache row");
+    }
+}
+
+pub unsafe fn unborrow() {
+    CACHE.lock().unborrow();
+}
diff --git a/src/runtime/src/kernel/core1.rs b/src/runtime/src/kernel/core1.rs
index 000306f..b5c619c 100644
--- a/src/runtime/src/kernel/core1.rs
+++ b/src/runtime/src/kernel/core1.rs
@@ -19,6 +19,7 @@ use super::{
     KERNEL_CHANNEL_0TO1, KERNEL_CHANNEL_1TO0,
     KERNEL_IMAGE,
     Message,
+    cache
 };
 
 unsafe fn attribute_writeback(typeinfo: *const ()) {
@@ -170,6 +171,7 @@ pub fn main_core1() {
                     core1_rx = core::mem::replace(&mut *KERNEL_CHANNEL_0TO1.lock(), None).unwrap();
                     core1_tx = core::mem::replace(&mut *KERNEL_CHANNEL_1TO0.lock(), None).unwrap();
                 }
+                unsafe { cache::unborrow(); }
                 info!("kernel finished");
                 core1_tx.send(Message::KernelFinished);
             }
@@ -180,6 +182,8 @@ pub fn main_core1() {
 
 /// Called by eh_artiq
 pub fn terminate(exception: &'static eh_artiq::Exception<'static>, backtrace: &'static mut [usize]) -> ! {
+    unsafe { cache::unborrow(); }
+
     let load_addr = unsafe {
         KERNEL_IMAGE.as_ref().unwrap().get_load_addr()
     };
diff --git a/src/runtime/src/kernel/mod.rs b/src/runtime/src/kernel/mod.rs
index 10451a7..b3d94fb 100644
--- a/src/runtime/src/kernel/mod.rs
+++ b/src/runtime/src/kernel/mod.rs
@@ -10,6 +10,7 @@ pub mod core1;
 mod api;
 mod rpc;
 mod dma;
+mod cache;
 
 #[derive(Debug)]
 pub struct RPCException {