ref: ea413b4a62be9993e4b63bf237f0b1d482f4aafa
dir: /sys/src/libc/mips/atom.s/
/* * R4000 user-level atomic operations */ #define LL(base, rt) WORD $((060<<26)|((base)<<21)|((rt)<<16)) #define SC(base, rt) WORD $((070<<26)|((base)<<21)|((rt)<<16)) #define NOOP WORD $0x27 TEXT ainc(SB), 1, $-4 /* long ainc(long *); */ TEXT _xinc(SB), 1, $-4 /* void _xinc(long *); */ MOVW R1, R2 /* address of counter */ loop: MOVW $1, R3 LL(2, 1) NOOP ADD R1,R3,R3 SC(2, 3) NOOP BEQ R3,loop RET TEXT adec(SB), 1, $-4 /* long adec(long*); */ TEXT _xdec(SB), 1, $-4 /* long _xdec(long *); */ MOVW R1, R2 /* address of counter */ loop1: MOVW $-1, R3 LL(2, 1) NOOP ADD R1,R3,R3 MOVW R3, R1 SC(2, 3) NOOP BEQ R3,loop1 RET /* * int cas(uint* p, int ov, int nv); */ TEXT cas(SB), 1, $-4 MOVW ov+4(FP), R2 MOVW nv+8(FP), R3 spincas: LL(1, 4) /* R4 = *R1 */ NOOP BNE R2, R4, fail SC(1, 3) /* *R1 = R3 */ NOOP BEQ R3, spincas /* R3 == 0 means store failed */ MOVW $1, R1 RET fail: MOVW $0, R1 RET /* general-purpose abort */ _trap: MOVD $0, R0 MOVD 0(R0), R0 RET