//! Inline assembly implementing the routines exposed in `cortex_m::asm`.
//!
//! If the `inline-asm` feature is enabled, these functions will be directly called by the
//! `cortex-m` wrappers. Otherwise, `cortex-m` links against them via prebuilt archives.
//!
//! All of these functions should be blanket-`unsafe`. `cortex-m` provides safe wrappers where
//! applicable.
use core::arch::asm;
use core::sync::atomic::{compiler_fence, Ordering};
#[inline(always)]
pub unsafe fn __bkpt() {
asm!("bkpt", options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __control_r() -> u32 {
let r;
asm!("mrs {}, CONTROL", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __control_w(w: u32) {
// ISB is required after writing to CONTROL,
// per ARM architectural requirements (see Application Note 321).
asm!(
"msr CONTROL, {}",
"isb",
in(reg) w,
options(nomem, nostack, preserves_flags),
);
// Ensure memory accesses are not reordered around the CONTROL update.
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __cpsid() {
asm!("cpsid i", options(nomem, nostack, preserves_flags));
// Ensure no subsequent memory accesses are reordered to before interrupts are disabled.
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __cpsie() {
// Ensure no preceeding memory accesses are reordered to after interrupts are enabled.
compiler_fence(Ordering::SeqCst);
asm!("cpsie i", options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __delay(cyc: u32) {
// The loop will normally take 3 to 4 CPU cycles per iteration, but superscalar cores
// (eg. Cortex-M7) can potentially do it in 2, so we use that as the lower bound, since delaying
// for more cycles is okay.
// Add 1 to prevent an integer underflow which would cause a long freeze
let real_cyc = 1 + cyc / 2;
asm!(
// Use local labels to avoid R_ARM_THM_JUMP8 relocations which fail on thumbv6m.
"1:",
"subs {}, #1",
"bne 1b",
inout(reg) real_cyc => _,
options(nomem, nostack),
);
}
#[inline(always)]
pub unsafe fn __dmb() {
compiler_fence(Ordering::SeqCst);
asm!("dmb", options(nomem, nostack, preserves_flags));
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __dsb() {
compiler_fence(Ordering::SeqCst);
asm!("dsb", options(nomem, nostack, preserves_flags));
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __isb() {
compiler_fence(Ordering::SeqCst);
asm!("isb", options(nomem, nostack, preserves_flags));
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __msp_r() -> u32 {
let r;
asm!("mrs {}, MSP", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __msp_w(val: u32) {
// Technically is writing to the stack pointer "not pushing any data to the stack"?
// In any event, if we don't set `nostack` here, this method is useless as the new
// stack value is immediately mutated by returning. Really this is just not a good
// method and its higher-level use is marked as deprecated in cortex-m.
asm!("msr MSP, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
// NOTE: No FFI shim, this requires inline asm.
#[inline(always)]
pub unsafe fn __apsr_r() -> u32 {
let r;
asm!("mrs {}, APSR", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __nop() {
// NOTE: This is a `pure` asm block, but applying that option allows the compiler to eliminate
// the nop entirely (or to collapse multiple subsequent ones). Since the user probably wants N
// nops when they call `nop` N times, let's not add that option.
asm!("nop", options(nomem, nostack, preserves_flags));
}
// NOTE: No FFI shim, this requires inline asm.
#[inline(always)]
pub unsafe fn __pc_r() -> u32 {
let r;
asm!("mov {}, pc", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
// NOTE: No FFI shim, this requires inline asm.
#[inline(always)]
pub unsafe fn __pc_w(val: u32) {
asm!("mov pc, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
// NOTE: No FFI shim, this requires inline asm.
#[inline(always)]
pub unsafe fn __lr_r() -> u32 {
let r;
asm!("mov {}, lr", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
// NOTE: No FFI shim, this requires inline asm.
#[inline(always)]
pub unsafe fn __lr_w(val: u32) {
asm!("mov lr, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __primask_r() -> u32 {
let r;
asm!("mrs {}, PRIMASK", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __psp_r() -> u32 {
let r;
asm!("mrs {}, PSP", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __psp_w(val: u32) {
// See comment on __msp_w. Unlike MSP, there are legitimate use-cases for modifying PSP
// if MSP is currently being used as the stack pointer.
asm!("msr PSP, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __sev() {
asm!("sev", options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __udf() -> ! {
asm!("udf #0", options(noreturn, nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __wfe() {
asm!("wfe", options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __wfi() {
asm!("wfi", options(nomem, nostack, preserves_flags));
}
/// Semihosting syscall.
#[inline(always)]
pub unsafe fn __sh_syscall(mut nr: u32, arg: u32) -> u32 {
asm!("bkpt #0xab", inout("r0") nr, in("r1") arg, options(nomem, nostack, preserves_flags));
nr
}
/// Set CONTROL.SPSEL to 0, write `msp` to MSP, branch to `rv`.
#[inline(always)]
pub unsafe fn __bootstrap(msp: u32, rv: u32) -> ! {
asm!(
"mrs {tmp}, CONTROL",
"bics {tmp}, {spsel}",
"msr CONTROL, {tmp}",
"isb",
"msr MSP, {msp}",
"bx {rv}",
// `out(reg) _` is not permitted in a `noreturn` asm! call,
// so instead use `in(reg) 0` and don't restore it afterwards.
tmp = in(reg) 0,
spsel = in(reg) 2,
msp = in(reg) msp,
rv = in(reg) rv,
options(noreturn, nomem, nostack),
);
}
// v7m *AND* v8m.main, but *NOT* v8m.base
#[cfg(any(armv7m, armv8m_main))]
pub use self::v7m::*;
#[cfg(any(armv7m, armv8m_main))]
mod v7m {
use core::arch::asm;
use core::sync::atomic::{compiler_fence, Ordering};
#[inline(always)]
pub unsafe fn __basepri_max(val: u8) {
asm!("msr BASEPRI_MAX, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __basepri_r() -> u8 {
let r;
asm!("mrs {}, BASEPRI", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __basepri_w(val: u8) {
asm!("msr BASEPRI, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __faultmask_r() -> u32 {
let r;
asm!("mrs {}, FAULTMASK", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __enable_icache() {
asm!(
"ldr {0}, =0xE000ED14", // CCR
"mrs {2}, PRIMASK", // save critical nesting info
"cpsid i", // mask interrupts
"ldr {1}, [{0}]", // read CCR
"orr.w {1}, {1}, #(1 << 17)", // Set bit 17, IC
"str {1}, [{0}]", // write it back
"dsb", // ensure store completes
"isb", // synchronize pipeline
"msr PRIMASK, {2}", // unnest critical section
out(reg) _,
out(reg) _,
out(reg) _,
options(nostack),
);
compiler_fence(Ordering::SeqCst);
}
#[inline(always)]
pub unsafe fn __enable_dcache() {
asm!(
"ldr {0}, =0xE000ED14", // CCR
"mrs {2}, PRIMASK", // save critical nesting info
"cpsid i", // mask interrupts
"ldr {1}, [{0}]", // read CCR
"orr.w {1}, {1}, #(1 << 16)", // Set bit 16, DC
"str {1}, [{0}]", // write it back
"dsb", // ensure store completes
"isb", // synchronize pipeline
"msr PRIMASK, {2}", // unnest critical section
out(reg) _,
out(reg) _,
out(reg) _,
options(nostack),
);
compiler_fence(Ordering::SeqCst);
}
}
#[cfg(armv7em)]
pub use self::v7em::*;
#[cfg(armv7em)]
mod v7em {
use core::arch::asm;
#[inline(always)]
pub unsafe fn __basepri_max_cm7_r0p1(val: u8) {
asm!(
"mrs {1}, PRIMASK",
"cpsid i",
"tst.w {1}, #1",
"msr BASEPRI_MAX, {0}",
"it ne",
"bxne lr",
"cpsie i",
in(reg) val,
out(reg) _,
options(nomem, nostack, preserves_flags),
);
}
#[inline(always)]
pub unsafe fn __basepri_w_cm7_r0p1(val: u8) {
asm!(
"mrs {1}, PRIMASK",
"cpsid i",
"tst.w {1}, #1",
"msr BASEPRI, {0}",
"it ne",
"bxne lr",
"cpsie i",
in(reg) val,
out(reg) _,
options(nomem, nostack, preserves_flags),
);
}
}
#[cfg(armv8m)]
pub use self::v8m::*;
/// Baseline and Mainline.
#[cfg(armv8m)]
mod v8m {
use core::arch::asm;
#[inline(always)]
pub unsafe fn __tt(mut target: u32) -> u32 {
asm!(
"tt {target}, {target}",
target = inout(reg) target,
options(nomem, nostack, preserves_flags),
);
target
}
#[inline(always)]
pub unsafe fn __ttt(mut target: u32) -> u32 {
asm!(
"ttt {target}, {target}",
target = inout(reg) target,
options(nomem, nostack, preserves_flags),
);
target
}
#[inline(always)]
pub unsafe fn __tta(mut target: u32) -> u32 {
asm!(
"tta {target}, {target}",
target = inout(reg) target,
options(nomem, nostack, preserves_flags),
);
target
}
#[inline(always)]
pub unsafe fn __ttat(mut target: u32) -> u32 {
asm!(
"ttat {target}, {target}",
target = inout(reg) target,
options(nomem, nostack, preserves_flags),
);
target
}
#[inline(always)]
pub unsafe fn __msp_ns_r() -> u32 {
let r;
asm!("mrs {}, MSP_NS", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __msp_ns_w(val: u32) {
asm!("msr MSP_NS, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __bxns(val: u32) {
asm!("BXNS {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
}
#[cfg(armv8m_main)]
pub use self::v8m_main::*;
/// Mainline only.
#[cfg(armv8m_main)]
mod v8m_main {
use core::arch::asm;
#[inline(always)]
pub unsafe fn __msplim_r() -> u32 {
let r;
asm!("mrs {}, MSPLIM", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __msplim_w(val: u32) {
asm!("msr MSPLIM, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
#[inline(always)]
pub unsafe fn __psplim_r() -> u32 {
let r;
asm!("mrs {}, PSPLIM", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __psplim_w(val: u32) {
asm!("msr PSPLIM, {}", in(reg) val, options(nomem, nostack, preserves_flags));
}
}
#[cfg(has_fpu)]
pub use self::fpu::*;
/// All targets with FPU.
#[cfg(has_fpu)]
mod fpu {
use core::arch::asm;
#[inline(always)]
pub unsafe fn __fpscr_r() -> u32 {
let r;
asm!("vmrs {}, fpscr", out(reg) r, options(nomem, nostack, preserves_flags));
r
}
#[inline(always)]
pub unsafe fn __fpscr_w(val: u32) {
asm!("vmsr fpscr, {}", in(reg) val, options(nomem, nostack));
}
}
witch'/>
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Jarred Sumner
Ashcon Partovi
João Paquim