/* *	mpvecsub(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *diff) * *		diff[0:alen-1] = a[0:alen-1] - b[0:blen-1] * *	prereq: alen >= blen, diff has room for alen digits */TEXT	mpvecsub(SB),$0 /*	MOVQ	a+0(FP),SI */	MOVQ	RARG, SI	MOVQ	b+16(FP),BX	MOVL	alen+8(FP),DX	MOVL	blen+24(FP),CX	MOVQ	diff+32(FP),DI	SUBL	CX,DX	XORL	BP,BP			/* this also sets carry to 0 */ 	/* skip subraction if b is zero */	TESTL	CX,CX	JZ	_sub1 	/* diff[0:blen-1],borrow = a[0:blen-1] - b[0:blen-1] */_subloop1:	MOVL	(SI)(BP*4),AX	SBBL	(BX)(BP*4),AX	MOVL	AX,(DI)(BP*4)	INCL	BP	LOOP	_subloop1 _sub1:	INCL	DX	MOVL	DX,CX	LOOP	_subloop2	RET 	/* diff[blen:alen-1] = a[blen:alen-1] - 0 */_subloop2:	MOVL	(SI)(BP*4),AX	SBBL	$0,AX	MOVL	AX,(DI)(BP*4)	INCL	BP	LOOP	_subloop2	RET