forked from M-Labs/artiq
40 lines
982 B
Rust
40 lines
982 B
Rust
use core::ptr::{read_volatile, write_volatile};
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use board_misoc::{mem, cache};
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const MAILBOX: *mut usize = mem::MAILBOX_BASE as *mut usize;
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static mut LAST: usize = 0;
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pub unsafe fn send(data: usize) {
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LAST = data;
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// after Rust toolchain update to LLVM12, this empty asm! block is required
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// to ensure that the compiler doesn't take any shortcuts
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// otherwise, the comm CPU will read garbage data and crash
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asm!("", options(preserves_flags, readonly, nostack));
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write_volatile(MAILBOX, data);
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}
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pub fn acknowledged() -> bool {
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unsafe {
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let data = read_volatile(MAILBOX);
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data == 0 || data != LAST
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}
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}
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pub fn receive() -> usize {
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unsafe {
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let data = read_volatile(MAILBOX);
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if data == LAST {
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0
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} else {
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if data != 0 {
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cache::flush_cpu_dcache()
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}
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data
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}
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}
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}
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pub fn acknowledge() {
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unsafe { write_volatile(MAILBOX, 0) }
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}
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