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- /*
- * mpvecdigmul(mpdigit *b, int n, mpdigit m, mpdigit *p)
- *
- * p += b*m
- *
- * each step look like:
- * hi,lo = m*b[i]
- * lo += oldhi + carry
- * hi += carry
- * p[i] += lo
- * oldhi = hi
- *
- * the registers are:
- * hi = DX - constrained by hardware
- * lo = AX - constrained by hardware
- * b+n = SI - can't be BP
- * p+n = DI - can't be BP
- * i-n = BP
- * m = BX
- * oldhi = CX
- *
- */
- TEXT mpvecdigmuladd(SB),$0
- MOVL b+0(FP),SI
- MOVL n+4(FP),CX
- MOVL m+8(FP),BX
- MOVL p+12(FP),DI
- MOVL CX,BP
- NEGL BP /* BP = -n */
- SHLL $2,CX
- ADDL CX,SI /* SI = b + n */
- ADDL CX,DI /* DI = p + n */
- XORL CX,CX
- _muladdloop:
- MOVL (SI)(BP*4),AX /* lo = b[i] */
- MULL BX /* hi, lo = b[i] * m */
- ADDL CX,AX /* lo += oldhi */
- JCC _muladdnocarry1
- INCL DX /* hi += carry */
- _muladdnocarry1:
- ADDL AX,(DI)(BP*4) /* p[i] += lo */
- JCC _muladdnocarry2
- INCL DX /* hi += carry */
- _muladdnocarry2:
- MOVL DX,CX /* oldhi = hi */
- INCL BP /* i++ */
- JNZ _muladdloop
- XORL AX,AX
- ADDL CX,(DI)(BP*4) /* p[n] + oldhi */
- ADCL AX,AX /* return carry out of p[n] */
- RET
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