refactor(sha): decouple BSWAP masks from SHA round-constant arrays#80
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The x86 SIMD kernels previously appended a pshufb byte-swap mask to the end
of the K256/K512/K_SHA1 round-constant arrays and reached it via an offset
from the constants pointer (e.g. [r9+$100]). This conflated two unrelated
things: the algorithm's round constants and an x86-only implementation
detail, and it bloated the public K arrays with values that are not part of
the SHA specification.
Separate the two concerns:
- Shrink K256 [0..63], K512 [0..79] and K_SHA1 [0..15] back to exactly the
spec-defined round constants.
- Introduce dedicated BSWAP32_MASK / BSWAP64_MASK constants, guarded by
{$IFDEF HASHLIB_X86_SIMD} since they are an x86 SIMD concern only (ARM
byte-swaps natively via REV32/REV64 and needs no mask table).
- Pass the mask as a separate 5th pointer argument: the SSSE3/AVX2/SHA-NI
compress procedures now use SimdProc5Begin instead of SimdProc4Begin, and
the kernels load the mask from the dedicated pointer (r10 on x86-64, ecx
on i386) instead of an offset past the constants. SSE2 backends are
unchanged (they byte-swap without a mask).
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The x86 SIMD kernels previously appended a pshufb byte-swap mask to the end of the K256/K512/K_SHA1 round-constant arrays and reached it via an offset from the constants pointer (e.g. [r9+$100]). This conflated two unrelated things: the algorithm's round constants and an x86-only implementation detail, and it bloated the public K arrays with values that are not part of the SHA specification.
Separate the two concerns: