ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: /libkern/memset-mips.s/
TEXT memset(SB),$12 MOVW R1, 0(FP) /* * performance: * about 1us/call and 28mb/sec */ MOVW n+8(FP), R3 /* R3 is count */ MOVW p+0(FP), R4 /* R4 is pointer */ MOVW c+4(FP), R5 /* R5 is char */ ADDU R3,R4, R6 /* R6 is end pointer */ /* * if not at least 4 chars, * dont 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. */ SGT $4,R3, R1 BNE R1, out /* * turn R5 into a word of characters */ AND $0xff, R5 SLL $8,R5, R1 OR R1, R5 SLL $16,R5, R1 OR R1, R5 /* * store one byte at a time until pointer * is alligned on a word boundary */ l1: AND $3,R4, R1 BEQ R1, l2 MOVB R5, 0(R4) ADDU $1, R4 JMP l1 /* * turn R3 into end pointer-15 * store 16 at a time while theres room */ l2: ADDU $-15,R6, R3 l3: SGTU R3,R4, R1 BEQ R1, l4 MOVW R5, 0(R4) MOVW R5, 4(R4) ADDU $16, R4 MOVW R5, -8(R4) MOVW R5, -4(R4) JMP l3 /* * turn R3 into end pointer-3 * store 4 at a time while theres room */ l4: ADDU $-3,R6, R3 l5: SGTU R3,R4, R1 BEQ R1, out MOVW R5, 0(R4) ADDU $4, R4 JMP l5 /* * last loop, store byte at a time */ out: SGTU R6,R4 ,R1 BEQ R1, ret MOVB R5, 0(R4) ADDU $1, R4 JMP out ret: MOVW s1+0(FP), R1 RET END