diff options
Diffstat (limited to 'libmp/Plan9-amd64/mpvecadd.s')
| -rw-r--r-- | libmp/Plan9-amd64/mpvecadd.s | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/libmp/Plan9-amd64/mpvecadd.s b/libmp/Plan9-amd64/mpvecadd.s new file mode 100644 index 00000000..326f39da --- /dev/null +++ b/libmp/Plan9-amd64/mpvecadd.s @@ -0,0 +1,54 @@ +/* + * mpvecadd(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *sum) + * + * sum[0:alen] = a[0:alen-1] + b[0:blen-1] + * + * prereq: alen >= blen, sum has room for alen+1 digits + */ +TEXT mpvecadd(SB),$0 + + MOVL alen+8(FP),DX + MOVL blen+24(FP),CX +/* MOVL a+0(FP),SI */ + MOVQ RARG, SI + MOVQ b+16(FP),BX + SUBL CX,DX + MOVQ sum+32(FP),DI + XORL BP,BP /* this also sets carry to 0 */ + + /* skip addition if b is zero */ + TESTL CX,CX + JZ _add1 + + /* sum[0:blen-1],carry = a[0:blen-1] + b[0:blen-1] */ +_addloop1: + MOVL (SI)(BP*4), AX + ADCL (BX)(BP*4), AX + MOVL AX,(DI)(BP*4) + INCL BP + LOOP _addloop1 + +_add1: + /* jump if alen > blen */ + INCL DX + MOVL DX,CX + LOOP _addloop2 + + /* sum[alen] = carry */ +_addend: + JC _addcarry + MOVL $0,(DI)(BP*4) + RET +_addcarry: + MOVL $1,(DI)(BP*4) + RET + + /* sum[blen:alen-1],carry = a[blen:alen-1] + 0 */ +_addloop2: + MOVL (SI)(BP*4),AX + ADCL $0,AX + MOVL AX,(DI)(BP*4) + INCL BP + LOOP _addloop2 + JMP _addend + |