diff options
Diffstat (limited to 'src/internal/bytealg/compare_arm.s')
| -rw-r--r-- | src/internal/bytealg/compare_arm.s | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/src/internal/bytealg/compare_arm.s b/src/internal/bytealg/compare_arm.s new file mode 100644 index 0000000..80d01a2 --- /dev/null +++ b/src/internal/bytealg/compare_arm.s @@ -0,0 +1,86 @@ +// Copyright 2018 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#include "go_asm.h" +#include "textflag.h" + +TEXT ·Compare(SB),NOSPLIT|NOFRAME,$0-28 + MOVW a_base+0(FP), R2 + MOVW a_len+4(FP), R0 + MOVW b_base+12(FP), R3 + MOVW b_len+16(FP), R1 + ADD $28, R13, R7 + B cmpbody<>(SB) + +TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-20 + MOVW a_base+0(FP), R2 + MOVW a_len+4(FP), R0 + MOVW b_base+8(FP), R3 + MOVW b_len+12(FP), R1 + ADD $20, R13, R7 + B cmpbody<>(SB) + +// On entry: +// R0 is the length of a +// R1 is the length of b +// R2 points to the start of a +// R3 points to the start of b +// R7 points to return value (-1/0/1 will be written here) +// +// On exit: +// R4, R5, R6 and R8 are clobbered +TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0-0 + CMP R2, R3 + BEQ samebytes + CMP R0, R1 + MOVW R0, R6 + MOVW.LT R1, R6 // R6 is min(R0, R1) + + CMP $0, R6 + BEQ samebytes + CMP $4, R6 + ADD R2, R6 // R2 is current byte in a, R6 is the end of the range to compare + BLT byte_loop // length < 4 + AND $3, R2, R8 + CMP $0, R8 + BNE byte_loop // unaligned a, use byte-wise compare (TODO: try to align a) +aligned_a: + AND $3, R3, R8 + CMP $0, R8 + BNE byte_loop // unaligned b, use byte-wise compare + AND $0xfffffffc, R6, R8 + // length >= 4 +chunk4_loop: + MOVW.P 4(R2), R4 + MOVW.P 4(R3), R5 + CMP R4, R5 + BNE cmp + CMP R2, R8 + BNE chunk4_loop + CMP R2, R6 + BEQ samebytes // all compared bytes were the same; compare lengths +byte_loop: + MOVBU.P 1(R2), R4 + MOVBU.P 1(R3), R5 + CMP R4, R5 + BNE ret + CMP R2, R6 + BNE byte_loop +samebytes: + CMP R0, R1 + MOVW.LT $1, R0 + MOVW.GT $-1, R0 + MOVW.EQ $0, R0 + MOVW R0, (R7) + RET +ret: + // bytes differed + MOVW.LT $1, R0 + MOVW.GT $-1, R0 + MOVW R0, (R7) + RET +cmp: + SUB $4, R2, R2 + SUB $4, R3, R3 + B byte_loop |