18461079395

Committed 13 Oct 2025 09:20AM UTC coverage: 42.731% (-0.9%) from 43.668%

Build # 18461079395

Build Type

Pull #536

github

Committed by

web-flow

Commit Message

Merge 6f55a8b56 into e378cba22

Pull Request Pull Request #536: Initial proposal for no_std support

Run Details

63 of 755 new or added lines in 38 files covered. (8.34%)

73 existing lines in 15 files now uncovered.

12324 of 28841 relevant lines covered (42.73%)

3215759.81 hits per line

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0.0

/crates/steel-core/src/getrandom_custom.rs

//! Custom fallback for `getrandom` when the `std` feature is disabled.
//!
//! The implementation below provides a deterministic, non-cryptographic source of
//! bytes so code that depends on `getrandom` (e.g. tests or hashing seeds) keeps
//! working in `no_std` builds without relying on the `wasm_js` backend.

use core::slice;
use getrandom::Error;

#[inline]
fn stir(mut state: u64) -> u64 {
    // xorshift64*; good enough for seeding hashers in no_std builds.
    state ^= state >> 12;
    state ^= state << 25;
    state ^= state >> 27;
    state.wrapping_mul(0x2545_F491_4F6C_DD1D)
}

fn fill_buffer(buf: &mut [u8], mut state: u64) {
    for byte in buf.iter_mut() {
        state = stir(state);
        *byte = (state >> 56) as u8;
    }
}

#[no_mangle]
pub unsafe extern "Rust" fn __getrandom_v03_custom(dest: *mut u8, len: usize) -> Result<(), Error> {
    if len == 0 {
        return Ok(());
    }

    if dest.is_null() {
        return Err(Error::UNSUPPORTED);
    }

    let buf = unsafe { slice::from_raw_parts_mut(dest, len) };
    let base = dest as usize as u64;
    let seed = 0xA076_1D64_78BD_642F ^ base.rotate_left(17) ^ (len as u64);
    fill_buffer(buf, seed);
    Ok(())
}

1	//! Custom fallback for `getrandom` when the `std` feature is disabled.
2	//!
3	//! The implementation below provides a deterministic, non-cryptographic source of
4	//! bytes so code that depends on `getrandom` (e.g. tests or hashing seeds) keeps
5	//! working in `no_std` builds without relying on the `wasm_js` backend.
6
7	use core::slice;
8	use getrandom::Error;
9
10	#[inline]
NEW 11	fn stir(mut state: u64) -> u64 {	×
12	// xorshift64*; good enough for seeding hashers in no_std builds.
NEW 13	state ^= state >> 12;	×
NEW 14	state ^= state << 25;	×
NEW 15	state ^= state >> 27;	×
NEW 16	state.wrapping_mul(0x2545_F491_4F6C_DD1D)	×
17	}
18
19	fn fill_buffer(buf: &mut [u8], mut state: u64) {
20	for byte in buf.iter_mut() {
21	state = stir(state);
22	*byte = (state >> 56) as u8;
23	}
24	}
25
26	#[no_mangle]
27	pub unsafe extern "Rust" fn __getrandom_v03_custom(dest: *mut u8, len: usize) -> Result<(), Error> {
28	if len == 0 {
29	return Ok(());
30	}
31
32	if dest.is_null() {
33	return Err(Error::UNSUPPORTED);
34	}
35
36	let buf = unsafe { slice::from_raw_parts_mut(dest, len) };
37	let base = dest as usize as u64;
38	let seed = 0xA076_1D64_78BD_642F ^ base.rotate_left(17) ^ (len as u64);
39	fill_buffer(buf, seed);
40	Ok(())
41	}

mattwparas / steel / 18461079395

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