ref: a0cc369c15bdd404e1a60b4fd5b3a5156a041f74
dir: /sys/src/libc/mips/memmove.s/
TEXT memmove(SB), $0 JMP move TEXT memcpy(SB), $0 move: MOVW R1, s1+0(FP) MOVW n+8(FP), R3 /* R3 is count */ MOVW R1, R4 /* R4 is to-pointer */ SGT R0, R3, R5 BEQ R5, ok MOVW (R0), R0 /* abort if negative count */ ok: MOVW s2+4(FP), R5 /* R5 is from-pointer */ ADDU R3,R5, R7 /* R7 is end from-pointer */ ADDU R3,R4, R6 /* R6 is end to-pointer */ /* * easiest test is copy backwards if * destination string has higher mem address */ SGT $4,R3, R2 SGTU R4,R5, R1 BNE R1, back /* * if not at least 4 chars, * don't even mess around. * 3 chars to guarantee any * rounding up to a word * boundary and 4 characters * to get at least maybe one * full word store. */ BNE R2, fout /* * byte at a time to word align destination */ f1: AND $3,R4, R1 BEQ R1, f2 MOVB 0(R5), R8 ADDU $1, R5 MOVB R8, 0(R4) ADDU $1, R4 JMP f1 /* * test if source is now word aligned */ f2: AND $3, R5, R1 BNE R1, fun2 /* * turn R3 into to-end pointer-15 * copy 16 at a time while theres room. * R6 is smaller than R7 -- * there are problems if R7 is 0. */ ADDU $-15,R6, R3 f3: SGTU R3,R4, R1 BEQ R1, f4 MOVW 0(R5), R8 MOVW 4(R5), R9 MOVW R8, 0(R4) MOVW 8(R5), R8 MOVW R9, 4(R4) MOVW 12(R5), R9 ADDU $16, R5 MOVW R8, 8(R4) MOVW R9, 12(R4) ADDU $16, R4 JMP f3 /* * turn R3 into to-end pointer-3 * copy 4 at a time while theres room */ f4: ADDU $-3,R6, R3 f5: SGTU R3,R4, R1 BEQ R1, fout MOVW 0(R5), R8 ADDU $4, R5 MOVW R8, 0(R4) ADDU $4, R4 JMP f5 /* * forward copy, unaligned * turn R3 into to-end pointer-15 * copy 16 at a time while theres room. * R6 is smaller than R7 -- * there are problems if R7 is 0. */ fun2: ADDU $-15,R6, R3 fun3: SGTU R3,R4, R1 BEQ R1, fun4 MOVWL 0(R5), R8 MOVWR 3(R5), R8 MOVWL 4(R5), R9 MOVWR 7(R5), R9 MOVW R8, 0(R4) MOVWL 8(R5), R8 MOVWR 11(R5), R8 MOVW R9, 4(R4) MOVWL 12(R5), R9 MOVWR 15(R5), R9 ADDU $16, R5 MOVW R8, 8(R4) MOVW R9, 12(R4) ADDU $16, R4 JMP fun3 /* * turn R3 into to-end pointer-3 * copy 4 at a time while theres room */ fun4: ADDU $-3,R6, R3 fun5: SGTU R3,R4, R1 BEQ R1, fout MOVWL 0(R5), R8 MOVWR 3(R5), R8 ADDU $4, R5 MOVW R8, 0(R4) ADDU $4, R4 JMP fun5 /* * last loop, copy byte at a time */ fout: BEQ R7,R5, ret MOVB 0(R5), R8 ADDU $1, R5 MOVB R8, 0(R4) ADDU $1, R4 JMP fout /* * whole thing repeated for backwards */ back: BNE R2, bout b1: AND $3,R6, R1 BEQ R1, b2 MOVB -1(R7), R8 ADDU $-1, R7 MOVB R8, -1(R6) ADDU $-1, R6 JMP b1 b2: AND $3, R7, R1 BNE R1, bun2 ADDU $15,R5, R3 b3: SGTU R7,R3, R1 BEQ R1, b4 MOVW -4(R7), R8 MOVW -8(R7), R9 MOVW R8, -4(R6) MOVW -12(R7), R8 MOVW R9, -8(R6) MOVW -16(R7), R9 ADDU $-16, R7 MOVW R8, -12(R6) MOVW R9, -16(R6) ADDU $-16, R6 JMP b3 b4: ADDU $3,R5, R3 b5: SGTU R7,R3, R1 BEQ R1, bout MOVW -4(R7), R8 ADDU $-4, R7 MOVW R8, -4(R6) ADDU $-4, R6 JMP b5 bun2: ADDU $15,R5, R3 bun3: SGTU R7,R3, R1 BEQ R1, bun4 MOVWL -4(R7), R8 MOVWR -1(R7), R8 MOVWL -8(R7), R9 MOVWR -5(R7), R9 MOVW R8, -4(R6) MOVWL -12(R7), R8 MOVWR -9(R7), R8 MOVW R9, -8(R6) MOVWL -16(R7), R9 MOVWR -13(R7), R9 ADDU $-16, R7 MOVW R8, -12(R6) MOVW R9, -16(R6) ADDU $-16, R6 JMP bun3 bun4: ADDU $3,R5, R3 bun5: SGTU R7,R3, R1 BEQ R1, bout MOVWL -4(R7), R8 MOVWR -1(R7), R8 ADDU $-4, R7 MOVW R8, -4(R6) ADDU $-4, R6 JMP bun5 bout: BEQ R7,R5, ret MOVB -1(R7), R8 ADDU $-1, R7 MOVB R8, -1(R6) ADDU $-1, R6 JMP bout ret: MOVW s1+0(FP), R1 RET END