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| 1 // Copyright 2009 The Go Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style | |
| 3 // license that can be found in the LICENSE file. | |
| 4 | |
| 5 #include "arm/asm.h" | |
| 6 | |
| 7 // This version works on pre v6 architectures | |
| 8 | |
| 9 // bool cas(int32 *val, int32 old, int32 new) | |
| 10 // Atomically: | |
| 11 // if(*val == old){ | |
| 12 // *val = new; | |
| 13 // return 1; | |
| 14 // }else | |
| 15 // return 0; | |
| 16 | |
| 17 TEXT runtime·cas(SB),7,$0 | |
| 18 MOVW 0(FP), R0 // *val | |
| 19 MOVW 4(FP), R1 // old | |
| 20 MOVW 8(FP), R2 // new | |
| 21 MOVW $1, R3 | |
| 22 MOVW $runtime·cas_mutex(SB), R4 | |
| 23 SWPW (R4), R3 // acquire mutex | |
| 24 CMP $0, R3 | |
| 25 BNE fail0 | |
| 26 ········ | |
| 27 MOVW (R0), R5 | |
| 28 CMP R1, R5 | |
| 29 BNE fail1 | |
| 30 ········ | |
| 31 MOVW R2, (R0)········ | |
| 32 MOVW R3, (R4) // release mutex | |
| 33 MOVW $1, R0 | |
| 34 RET | |
| 35 fail1:·· | |
| 36 MOVW R3, (R4) // release mutex | |
| 37 fail0: | |
| 38 MOVW $0, R0 | |
| 39 RET | |
| 40 | |
| 41 // bool casp(void **p, void *old, void *new) | |
| 42 // Atomically: | |
| 43 // if(*p == old){ | |
| 44 // *p = new; | |
| 45 // return 1; | |
| 46 // }else | |
| 47 // return 0; | |
| 48 | |
| 49 TEXT runtime·casp(SB),7,$0 | |
| 50 MOVW 0(FP), R0 // *p | |
| 51 MOVW 4(FP), R1 // old | |
| 52 MOVW 8(FP), R2 // new | |
| 53 MOVW $1, R3 | |
| 54 MOVW $runtime·cas_mutex(SB), R4 | |
| 55 SWPW (R4), R3 // acquire mutex | |
| 56 CMP $0, R3 | |
| 57 BNE failp0 | |
| 58 ········ | |
| 59 MOVW (R0), R5 | |
| 60 CMP R1, R5 | |
| 61 BNE failp1 | |
| 62 ········ | |
| 63 MOVW R2, (R0)········ | |
| 64 MOVW R3, (R4) // release mutex | |
| 65 MOVW $1, R0 | |
| 66 RET | |
| 67 failp1:· | |
| 68 MOVW R3, (R4) // release mutex | |
| 69 failp0: | |
| 70 MOVW $0, R0 | |
| 71 RET | |
| 72 | |
| 73 DATA runtime·cas_mutex(SB)/4, $0 | |
| 74 GLOBL runtime·cas_mutex(SB), $4 | |
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