ref: 380adf8b485ce93aa42ad0d414718c3ad4918176
dir: /sys/src/libmp/power/mpvecadd.s/
#define BDNZ BC 16,0, #define BDNE BC 0,2, /* * 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 * * R3 == a (first arg passed in R3) * R4 == alen * R5 == b * R6 == blen * R7 == sum * R8 == temporary * R9 == temporary */ TEXT mpvecadd(SB),$-4 MOVW alen+4(FP), R4 MOVW b+8(FP), R5 MOVW blen+12(FP), R6 MOVW sum+16(FP), R7 SUB R6, R4 /* calculate counter for second loop (alen > blen) */ SUB $4, R3 /* pre decrement for MOVWU's */ SUB $4, R5 /* pre decrement for MOVWU's */ SUB $4, R7 /* pre decrement for MOVWU's */ MOVW R0, XER /* zero carry going in */ /* if blen == 0, don't need to add it in */ CMP R0, R6 BEQ _add1 /* sum[0:blen-1],carry = a[0:blen-1] + b[0:blen-1] */ MOVW R6, CTR _addloop1: MOVWU 4(R3), R8 MOVWU 4(R5), R9 ADDE R8, R9 MOVWU R9, 4(R7) BDNZ _addloop1 _add1: /* if alen == blen, we're done */ CMP R0, R4 BEQ _addend /* sum[blen:alen-1],carry = a[blen:alen-1] + 0 + carry */ MOVW R4, CTR _addloop2: MOVWU 4(R3), R8 ADDE R0, R8 MOVWU R8, 4(R7) BDNZ _addloop2 /* sum[alen] = carry */ _addend: ADDE R0, R0, R8 MOVW R8, 4(R7) RETURN