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68 lines
1.2 KiB
68 lines
1.2 KiB
8 years ago
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build gc
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#define NOSPLIT 4
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#define RODATA 8
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// func castagnoliSSE42(crc uint32, p []byte) uint32
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TEXT ·castagnoliSSE42(SB), NOSPLIT, $0
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MOVL crc+0(FP), AX // CRC value
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MOVL p+4(FP), SI // data pointer
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MOVL p_len+8(FP), CX // len(p)
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NOTL AX
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// If there's less than 8 bytes to process, we do it byte-by-byte.
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CMPQ CX, $8
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JL cleanup
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// Process individual bytes until the input is 8-byte aligned.
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startup:
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MOVQ SI, BX
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ANDQ $7, BX
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JZ aligned
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CRC32B (SI), AX
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DECQ CX
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INCQ SI
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JMP startup
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aligned:
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// The input is now 8-byte aligned and we can process 8-byte chunks.
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CMPQ CX, $8
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JL cleanup
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CRC32Q (SI), AX
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ADDQ $8, SI
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SUBQ $8, CX
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JMP aligned
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cleanup:
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// We may have some bytes left over that we process one at a time.
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CMPQ CX, $0
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JE done
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CRC32B (SI), AX
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INCQ SI
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DECQ CX
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JMP cleanup
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done:
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NOTL AX
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MOVL AX, ret+16(FP)
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RET
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// func haveSSE42() bool
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TEXT ·haveSSE42(SB), NOSPLIT, $0
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XORQ AX, AX
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INCL AX
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CPUID
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SHRQ $20, CX
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ANDQ $1, CX
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MOVB CX, ret+0(FP)
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RET
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