Hojun-Cho
aadc6618f0
Every // ---- section banner dies (132 -> 0): names carry the WHAT. Narration deleted (filename restatements, run-with lines, what-the- next-line-does); every ref/hare cite, task cite, divergence, ABI/ layout contract, and ownership qualifier kept (borrowed-view lines restored where the sweep over-cut). Comment-only proven: all 442 walk-workdir .s and 32 import-probe .s byte-identical before/after; libbyteid 56-roster all-ID.
35 lines
981 B
Plaintext
35 lines
981 B
Plaintext
// Same shape as lib/hash/crc32: per-byte inline polynomial shift, no
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// precomputed table. Slower than Hare's table-driven path by ~8x per
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// byte but produces identical answers for the documented polynomials.
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//
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// Polynomials are given in reversed form, matching Hare.
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package crc64;
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def ECMA: u64 = 0xC96C5795D7870F42u64; // ECMA-182, xz-utils
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def ISO: u64 = 0xD800000000000000u64; // ISO 3309 HDLC
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// sum64 — fold `buf` under `poly` (reversed form). Initial cval is ~0u64.
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export fn sum64(buf: []u8, poly: u64) u64 = {
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let c: u64 = 0xFFFFFFFFFFFFFFFFu64;
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let i: i32 = 0;
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for (i < buf.len) {
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let t: u64 = (c & 0xFFu64) ^ (buf[i]: u64);
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let z: i32 = 0;
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for (z < 8) {
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if ((t & 1u64) == 1u64) {
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t = (t >> 1u64) ^ poly;
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} else {
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t = t >> 1u64;
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};
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z += 1;
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};
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c = t ^ (c >> 8u64);
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i += 1;
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};
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return ~c;
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};
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export fn sum64ecma(buf: []u8) u64 = { return sum64(buf, ECMA); };
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export fn sum64iso(buf: []u8) u64 = { return sum64(buf, ISO); };
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