46 lines
1.8 KiB
Text
46 lines
1.8 KiB
Text
# emit_schema_hash.ludic — Build.schema_hash(): FNV-1a 64 of the program's own schema (the bytes
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# `ludic schema` prints), so a tool talking to a running build can tell it was built from other
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# data. Worked out once, only when the program asks for it, and 0 in a release (`--release`,
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# ludic bundle). The compiler's int is 32 bits, so the hash is kept as four 16-bit limbs.
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var g_release: bool = false # --release: what ships carries no schema hash
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var g_uses_schema_hash: bool = false # the program names Build.schema_hash (parse.ludic)
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var g_sh_lo: int = 0 # the hash's low and high 32 bits, once worked out
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var g_sh_hi: int = 0
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var g_sh_done: bool = false
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# after the checker: the schema as --emit-schema would write it, hashed
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function schema_hash_compute() -> void {
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if g_release or not g_uses_schema_hash { return }
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let b = schema_buf()
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let s = buf_str(b)
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var h0 = 8997 # 522109ce484222325, low limb first
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var h1 = 33826
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var h2 = 40164
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var h3 = 52210
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var i = 0
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while i < b.len {
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h0 = h0 ^ (s[i] & 255)
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# times 256000001b3: limb 0 of the prime is 435, limb 2 is 256
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var r0 = h0 * 435
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var r1 = h1 * 435 + (r0 >> 16)
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var r2 = h2 * 435 + h0 * 256 + (r1 >> 16)
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var r3 = h3 * 435 + h1 * 256 + (r2 >> 16)
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h0 = r0 & 65535
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h1 = r1 & 65535
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h2 = r2 & 65535
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h3 = r3 & 65535
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i += 1
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}
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g_sh_lo = (h1 << 16) | h0
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g_sh_hi = (h3 << 16) | h2
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g_sh_done = true
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}
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function is_build_ns(meth: pointer) -> bool { return meth == "schema_hash" }
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function emit_build_ns(meth: pointer, e: Node) -> Val {
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if not g_sh_done { return val("0", "long") }
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let lo = emit_bind(`zext i32 {itoa(g_sh_lo)} to i64`)
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let hi = emit_bind(`zext i32 {itoa(g_sh_hi)} to i64`)
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let up = emit_bind(`shl i64 {hi}, 32`)
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return val(emit_bind(`or i64 {up}, {lo}`), "long")
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}
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