ref: 8c6c2b7216b6039188e76d26f9a62c4cb8ee4fca
dir: /sys/src/libc/power/memmove.s/
#define BDNZ BC 16,0, TEXT memmove(SB), $0 BR move TEXT memcpy(SB), $0 move: /* * performance: * (tba) */ MOVW R3, s1+0(FP) MOVW n+8(FP), R9 /* R9 is count */ MOVW R3, R10 /* R10 is to-pointer */ CMP R9, $0 BEQ ret BLT trap MOVW s2+4(FP), R11 /* R11 is from-pointer */ /* * if no more than 16 bytes, just use one lsw/stsw */ CMP R9, $16 BLE fout ADD R9,R11, R13 /* R13 is end from-pointer */ ADD R9,R10, R12 /* R12 is end to-pointer */ /* * easiest test is copy backwards if * destination string has higher mem address */ CMPU R10, R11 BGT back /* * test if both pointers * are similarly word aligned */ XOR R10,R11, R7 ANDCC $3,R7 BNE fbad /* * move a few bytes to align pointers */ ANDCC $3,R10,R7 BEQ f2 SUBC R7, $4, R7 SUB R7, R9 MOVW R7, XER LSW (R11), R16 ADD R7, R11 STSW R16, (R10) ADD R7, R10 /* * turn R14 into doubleword count * copy 16 bytes at a time while there's room. */ f2: SRAWCC $4, R9, R14 BLE fout MOVW R14, CTR SUB $4, R11 SUB $4, R10 f3: MOVWU 4(R11), R16 MOVWU 4(R11), R17 MOVWU 4(R11), R18 MOVWU 4(R11), R19 MOVWU R16, 4(R10) MOVWU R17, 4(R10) MOVWU R18, 4(R10) MOVWU R19, 4(R10) BDNZ f3 RLWNMCC $0, R9, $15, R9 /* residue */ BEQ ret ADD $4, R11 ADD $4, R10 /* * move up to 16 bytes through R16 .. R19; aligned and unaligned */ fout: MOVW R9, XER LSW (R11), R16 STSW R16, (R10) BR ret /* * loop for unaligned copy, then copy up to 15 remaining bytes */ fbad: SRAWCC $4, R9, R14 BLE f6 MOVW R14, CTR f5: LSW (R11), $16, R16 ADD $16, R11 STSW R16, $16, (R10) ADD $16, R10 BDNZ f5 RLWNMCC $0, R9, $15, R9 /* residue */ BEQ ret f6: MOVW R9, XER LSW (R11), R16 STSW R16, (R10) BR ret /* * whole thing repeated for backwards */ back: CMP R9, $4 BLT bout XOR R12,R13, R7 ANDCC $3,R7 BNE bout b1: ANDCC $3,R13, R7 BEQ b2 MOVBZU -1(R13), R16 MOVBZU R16, -1(R12) SUB $1, R9 BR b1 b2: SRAWCC $4, R9, R14 BLE b4 MOVW R14, CTR b3: MOVWU -4(R13), R16 MOVWU -4(R13), R17 MOVWU -4(R13), R18 MOVWU -4(R13), R19 MOVWU R16, -4(R12) MOVWU R17, -4(R12) MOVWU R18, -4(R12) MOVWU R19, -4(R12) BDNZ b3 RLWNMCC $0, R9, $15, R9 /* residue */ BEQ ret b4: SRAWCC $2, R9, R14 BLE bout MOVW R14, CTR b5: MOVWU -4(R13), R16 MOVWU R16, -4(R12) BDNZ b5 RLWNMCC $0, R9, $3, R9 /* residue */ BEQ ret bout: CMPU R13, R11 BLE ret MOVBZU -1(R13), R16 MOVBZU R16, -1(R12) BR bout trap: MOVW $0, R0 MOVW 0(R0), R0 ret: MOVW s1+0(FP), R3 RETURN