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Take possible PIO program length of 32 into account (#350)

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Avoid overflow of left-shift operation by special-casing the value 32.

Fixes #349
This commit is contained in:
Jan Niehusmann 2022-06-01 23:03:04 +02:00 • committed by GitHub
parent d66b47920e
commit ed7148a1e7
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1 changed files with 14 additions and 4 deletions
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18
rp2040-hal/src/pio.rs
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@ -148,11 +148,21 @@ impl<P: PIOExt> PIO<P> {
.write(|w| unsafe { w.irq_force().bits(flags) });
}
/// Calculates a mask with the `len` right-most bits set.
fn instruction_mask(len: usize) -> u32 {
if len < 32 {
(1 << len) - 1
} else {
0xffffffff
}
}
/// Tries to find an appropriate offset for the instructions, in range 0..=31.
fn find_offset_for_instructions(&self, i: &[u16], origin: Option<u8>) -> Option<usize> {
if i.len() > PIO_INSTRUCTION_COUNT {
if i.len() > PIO_INSTRUCTION_COUNT || i.is_empty() {
None
} else {
let mask = (1 << i.len()) - 1;
let mask = Self::instruction_mask(i.len());
if let Some(origin) = origin {
if origin as usize > PIO_INSTRUCTION_COUNT - i.len()
|| self.used_instruction_space & (mask << origin) != 0
@ -208,7 +218,7 @@ impl<P: PIOExt> PIO<P> {
{
self.pio.instr_mem[i + offset].write(|w| unsafe { w.bits(instr as u32) })
}
self.used_instruction_space |= ((1 << p.code.len()) - 1) << offset;
self.used_instruction_space |= Self::instruction_mask(p.code.len()) << offset;
Ok(InstalledProgram {
offset: offset as u8,
length: p.code.len() as u8,
@ -223,7 +233,7 @@ impl<P: PIOExt> PIO<P> {
/// Removes the specified program from instruction memory, freeing the allocated space.
pub fn uninstall(&mut self, p: InstalledProgram<P>) {
let instr_mask = ((1 << p.length as u32) - 1) << p.offset as u32;
let instr_mask = Self::instruction_mask(p.length as usize) << p.offset as u32;
self.used_instruction_space &= !instr_mask;
}
}