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Use intrinsics.reverse_bits in core:compress/zlib

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Feoramund
2024-08-10 15:29:44 -04:00
parent 6918d8aaa6
commit cf8f6afeff
1 changed files with 2 additions and 7 deletions
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9
core/compress/zlib/zlib.odin
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@@ -12,6 +12,7 @@ package compress_zlib
import "core:compress"
import "base:intrinsics"
import "core:mem"
import "core:io"
import "core:hash"
@@ -123,13 +124,7 @@ Huffman_Table :: struct {
@(optimization_mode="favor_size")
z_bit_reverse :: #force_inline proc(n: u16, bits: u8) -> (r: u16) {
assert(bits <= 16)
// NOTE: Can optimize with llvm.bitreverse.i64 or some bit twiddling
// by reversing all of the bits and masking out the unneeded ones.
r = n
r = ((r & 0xAAAA) >> 1) | ((r & 0x5555) << 1)
r = ((r & 0xCCCC) >> 2) | ((r & 0x3333) << 2)
r = ((r & 0xF0F0) >> 4) | ((r & 0x0F0F) << 4)
r = ((r & 0xFF00) >> 8) | ((r & 0x00FF) << 8)
r = intrinsics.reverse_bits(n)
r >>= (16 - bits)
return