diff options
Diffstat (limited to 'libkern/memset-mips.s')
| -rw-r--r-- | libkern/memset-mips.s | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/libkern/memset-mips.s b/libkern/memset-mips.s new file mode 100644 index 00000000..8c9467f4 --- /dev/null +++ b/libkern/memset-mips.s @@ -0,0 +1,88 @@ + 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 |