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- // Copied from S2 implementation.
- //go:build !appengine && !noasm && gc && !noasm
- #include "textflag.h"
- // func matchLen(a []byte, b []byte) int
- // Requires: BMI
- TEXT ·matchLen(SB), NOSPLIT, $0-56
- MOVQ a_base+0(FP), AX
- MOVQ b_base+24(FP), CX
- MOVQ a_len+8(FP), DX
- // matchLen
- XORL SI, SI
- CMPL DX, $0x08
- JB matchlen_match4_standalone
- matchlen_loopback_standalone:
- MOVQ (AX)(SI*1), BX
- XORQ (CX)(SI*1), BX
- TESTQ BX, BX
- JZ matchlen_loop_standalone
- #ifdef GOAMD64_v3
- TZCNTQ BX, BX
- #else
- BSFQ BX, BX
- #endif
- SARQ $0x03, BX
- LEAL (SI)(BX*1), SI
- JMP gen_match_len_end
- matchlen_loop_standalone:
- LEAL -8(DX), DX
- LEAL 8(SI), SI
- CMPL DX, $0x08
- JAE matchlen_loopback_standalone
- matchlen_match4_standalone:
- CMPL DX, $0x04
- JB matchlen_match2_standalone
- MOVL (AX)(SI*1), BX
- CMPL (CX)(SI*1), BX
- JNE matchlen_match2_standalone
- LEAL -4(DX), DX
- LEAL 4(SI), SI
- matchlen_match2_standalone:
- CMPL DX, $0x02
- JB matchlen_match1_standalone
- MOVW (AX)(SI*1), BX
- CMPW (CX)(SI*1), BX
- JNE matchlen_match1_standalone
- LEAL -2(DX), DX
- LEAL 2(SI), SI
- matchlen_match1_standalone:
- CMPL DX, $0x01
- JB gen_match_len_end
- MOVB (AX)(SI*1), BL
- CMPB (CX)(SI*1), BL
- JNE gen_match_len_end
- INCL SI
- gen_match_len_end:
- MOVQ SI, ret+48(FP)
- RET
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