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Implement insertions for byte-level code gen

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Brian Carroll 2021-10-22 21:54:47 +02:00
parent dc1779d41d
commit bca9f31c58
2 changed files with 163 additions and 42 deletions
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22
compiler/gen_wasm/src/lib.rs
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@ -217,26 +217,32 @@ pub fn debug_panic<E: std::fmt::Debug>(error: E) {
panic!("{:?}", error);
}
/// Write a u32 value as LEB-128 encoded bytes, into the provided buffer
/// Write a u32 value as LEB-128 encoded bytes into the provided buffer, returning byte length
///
/// All integers in Wasm are variable-length encoded, which saves space for small values.
/// The most significant bit indicates "more bytes are coming", and the other 7 are payload.
pub fn encode_u32<'a>(buffer: &mut Vec<'a, u8>, mut value: u32) {
pub fn encode_u32<'a>(buffer: &mut [u8], mut value: u32) -> usize {
let mut count = 0;
while value >= 0x80 {
buffer.push(0x80 | ((value & 0x7f) as u8));
buffer[count] = 0x80 | ((value & 0x7f) as u8);
value >>= 7;
count += 1;
}
buffer.push(value as u8);
buffer[count] = value as u8;
count + 1
}
/// Write a u64 value as LEB-128 encoded bytes, into the provided buffer
/// Write a u64 value as LEB-128 encoded bytes, into the provided buffer, returning byte length
///
/// All integers in Wasm are variable-length encoded, which saves space for small values.
/// The most significant bit indicates "more bytes are coming", and the other 7 are payload.
pub fn encode_u64<'a>(buffer: &mut Vec<'a, u8>, mut value: u64) {
pub fn encode_u64<'a>(buffer: &mut Vec<'a, u8>, mut value: u64) -> usize {
let mut count = 0;
while value >= 0x80 {
buffer.push(0x80 | ((value & 0x7f) as u8));
buffer[count] = 0x80 | ((value & 0x7f) as u8);
value >>= 7;
count += 1;
}
buffer.push(value as u8);
buffer[count] = value as u8;
count + 1
}