1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

//! Miscellaneous assembly instructions

// When inline assembly is enabled, pull in the assembly routines here. `call_asm!` will invoke
// these routines.
#[cfg(feature = "inline-asm")]
#[path = "../asm/inline.rs"]
pub(crate) mod inline;

/// Puts the processor in Debug state. Debuggers can pick this up as a "breakpoint".
///
/// **NOTE** calling `bkpt` when the processor is not connected to a debugger will cause an
/// exception.
#[inline(always)]
pub fn bkpt() {
    call_asm!(__bkpt());
}

/// Blocks the program for *at least* `n` instruction cycles
///
/// This is implemented in assembly so its execution time is independent of the optimization
/// level, however it is dependent on the specific architecture and core configuration.
///
/// NOTE that the delay can take much longer if interrupts are serviced during its execution
/// and the execution time may vary with other factors. This delay is mainly useful for simple
/// timer-less initialization of peripherals if and only if accurate timing is not essential. In
/// any other case please use a more accurate method to produce a delay.
#[inline]
pub fn delay(n: u32) {
    // NOTE(divide by 4) is easier to compute than `/ 3` because it's just a shift (`>> 2`).
    let real_cyc = n / 4 + 1;
    call_asm!(__delay(real_cyc: u32));
}

/// A no-operation. Useful to prevent delay loops from being optimized away.
#[inline]
pub fn nop() {
    call_asm!(__nop());
}

/// Generate an Undefined Instruction exception.
///
/// Can be used as a stable alternative to `core::intrinsics::abort`.
#[inline]
pub fn udf() -> ! {
    call_asm!(__udf() -> !)
}

/// Wait For Event
#[inline]
pub fn wfe() {
    call_asm!(__wfe())
}

/// Wait For Interrupt
#[inline]
pub fn wfi() {
    call_asm!(__wfi())
}

/// Send Event
#[inline]
pub fn sev() {
    call_asm!(__sev())
}

/// Instruction Synchronization Barrier
///
/// Flushes the pipeline in the processor, so that all instructions following the `ISB` are fetched
/// from cache or memory, after the instruction has been completed.
#[inline]
pub fn isb() {
    call_asm!(__isb())
}

/// Data Synchronization Barrier
///
/// Acts as a special kind of memory barrier. No instruction in program order after this instruction
/// can execute until this instruction completes. This instruction completes only when both:
///
///  * any explicit memory access made before this instruction is complete
///  * all cache and branch predictor maintenance operations before this instruction complete
#[inline]
pub fn dsb() {
    call_asm!(__dsb())
}

/// Data Memory Barrier
///
/// Ensures that all explicit memory accesses that appear in program order before the `DMB`
/// instruction are observed before any explicit memory accesses that appear in program order
/// after the `DMB` instruction.
#[inline]
pub fn dmb() {
    call_asm!(__dmb())
}

/// Test Target
///
/// Queries the Security state and access permissions of a memory location.
/// Returns a Test Target Response Payload (cf section D1.2.215 of
/// Armv8-M Architecture Reference Manual).
#[inline]
#[cfg(armv8m)]
// The __tt function does not dereference the pointer received.
#[allow(clippy::not_unsafe_ptr_arg_deref)]
pub fn tt(addr: *mut u32) -> u32 {
    let addr = addr as u32;
    call_asm!(__tt(addr: u32) -> u32)
}

/// Test Target Unprivileged
///
/// Queries the Security state and access permissions of a memory location for an unprivileged
/// access to that location.
/// Returns a Test Target Response Payload (cf section D1.2.215 of
/// Armv8-M Architecture Reference Manual).
#[inline]
#[cfg(armv8m)]
// The __ttt function does not dereference the pointer received.
#[allow(clippy::not_unsafe_ptr_arg_deref)]
pub fn ttt(addr: *mut u32) -> u32 {
    let addr = addr as u32;
    call_asm!(__ttt(addr: u32) -> u32)
}

/// Test Target Alternate Domain
///
/// Queries the Security state and access permissions of a memory location for a Non-Secure access
/// to that location. This instruction is only valid when executing in Secure state and is
/// undefined if used from Non-Secure state.
/// Returns a Test Target Response Payload (cf section D1.2.215 of
/// Armv8-M Architecture Reference Manual).
#[inline]
#[cfg(armv8m)]
// The __tta function does not dereference the pointer received.
#[allow(clippy::not_unsafe_ptr_arg_deref)]
pub fn tta(addr: *mut u32) -> u32 {
    let addr = addr as u32;
    call_asm!(__tta(addr: u32) -> u32)
}

/// Test Target Alternate Domain Unprivileged
///
/// Queries the Security state and access permissions of a memory location for a Non-Secure and
/// unprivileged access to that location. This instruction is only valid when executing in Secure
/// state and is undefined if used from Non-Secure state.
/// Returns a Test Target Response Payload (cf section D1.2.215 of
/// Armv8-M Architecture Reference Manual).
#[inline]
#[cfg(armv8m)]
// The __ttat function does not dereference the pointer received.
#[allow(clippy::not_unsafe_ptr_arg_deref)]
pub fn ttat(addr: *mut u32) -> u32 {
    let addr = addr as u32;
    call_asm!(__ttat(addr: u32) -> u32)
}

/// Branch and Exchange Non-secure
///
/// See section C2.4.26 of Armv8-M Architecture Reference Manual for details.
/// Undefined if executed in Non-Secure state.
#[inline]
#[cfg(armv8m)]
pub unsafe fn bx_ns(addr: u32) {
    call_asm!(__bxns(addr: u32));
}