ref: c3ba64f6935322f09b6de5c2285544fd471c605d
dir: /sys/src/libc/power/memcmp.s/
TEXT memcmp(SB), $0 #define BDNZ BC 16,0, MOVW R3, s1+0(FP) /* R3 is pointer1 */ /* * performance: * 67mb/sec aligned; 16mb/sec unaligned */ MOVW n+8(FP), R4 /* R4 is count */ MOVW s2+4(FP), R5 /* R5 is pointer2 */ /* * let LSW do the work for 4 characters or less; aligned and unaligned */ CMP R4, $0 BLE eq CMP R4, $4 BLE out XOR R3, R5, R9 ANDCC $3, R9 BNE l4 /* pointers misaligned; use LSW loop */ /* * do enough bytes to align pointers */ ANDCC $3,R3, R9 BEQ l2 SUBC R9, $4, R9 MOVW R9, XER LSW (R3), R10 ADD R9, R3 LSW (R5), R14 ADD R9, R5 SUB R9, R4 CMPU R10, R14 BNE ne /* * compare 16 at a time */ l2: SRAWCC $4, R4, R9 BLE l4 MOVW R9, CTR SUB $4, R3 SUB $4, R5 l3: MOVWU 4(R3), R10 MOVWU 4(R5), R12 MOVWU 4(R3), R11 MOVWU 4(R5), R13 CMPU R10, R12 BNE ne MOVWU 4(R3), R10 MOVWU 4(R5), R12 CMPU R11, R13 BNE ne MOVWU 4(R3), R11 MOVWU 4(R5), R13 CMPU R10, R12 BNE ne CMPU R11, R13 BNE ne BDNZ l3 ADD $4, R3 ADD $4, R5 RLWNMCC $0, R4, $15, R4 /* residue */ BEQ eq /* * do remaining words with LSW; also does unaligned case */ l4: SRAWCC $2, R4, R9 BLE out MOVW R9, CTR l5: LSW (R3), $4, R10 ADD $4, R3 LSW (R5), $4, R11 ADD $4, R5 CMPU R10, R11 BNE ne BDNZ l5 RLWNMCC $0, R4, $3, R4 /* residue */ BEQ eq /* * do remaining bytes with final LSW */ out: MOVW R4, XER LSW (R3), R10 LSW (R5), R11 CMPU R10, R11 BNE ne eq: MOVW $0, R3 RETURN ne: MOVW $1, R3 BGE ret MOVW $-1,R3 ret: RETURN END