1 a32765e3 2005-08-10 devnull /*	mpvecsub(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *diff) */
 2 a32765e3 2005-08-10 devnull /*		diff[0:alen-1] = a[0:alen-1] - b[0:blen-1] */
 3 a32765e3 2005-08-10 devnull /*	prereq: alen >= blen, diff has room for alen digits */
 4 a32765e3 2005-08-10 devnull /* (very old gnu assembler doesn't allow multiline comments) */
 5 a32765e3 2005-08-10 devnull 
 6 ac0e2db6 2004-04-21 devnull .text
 7 ac0e2db6 2004-04-21 devnull 
 8 ac0e2db6 2004-04-21 devnull .p2align 2,0x90
 9 ac0e2db6 2004-04-21 devnull .globl mpvecsub
10 ac0e2db6 2004-04-21 devnull 	.type mpvecsub, @function
11 ac0e2db6 2004-04-21 devnull mpvecsub:
12 ac0e2db6 2004-04-21 devnull 	/* Prelude */
13 ac0e2db6 2004-04-21 devnull 	pushl %ebp
14 ac0e2db6 2004-04-21 devnull 	movl %ebx, -4(%esp)		/* save on stack */
15 ac0e2db6 2004-04-21 devnull 	movl %esi, -8(%esp)
16 ac0e2db6 2004-04-21 devnull 	movl %edi, -12(%esp)
17 ac0e2db6 2004-04-21 devnull 
18 ac0e2db6 2004-04-21 devnull 	movl	8(%esp), %esi		/* a */
19 ac0e2db6 2004-04-21 devnull 	movl	16(%esp), %ebx		/* b */
20 ac0e2db6 2004-04-21 devnull 	movl	12(%esp), %edx		/* alen */
21 ac0e2db6 2004-04-21 devnull 	movl	20(%esp), %ecx		/* blen */
22 ac0e2db6 2004-04-21 devnull 	movl	24(%esp), %edi		/* diff */
23 ac0e2db6 2004-04-21 devnull 	subl	%ecx,%edx
24 ac0e2db6 2004-04-21 devnull 	xorl	%ebp,%ebp			/* this also sets carry to 0 */
25 ac0e2db6 2004-04-21 devnull 
26 ac0e2db6 2004-04-21 devnull 	/* skip subraction if b is zero */
27 ac0e2db6 2004-04-21 devnull 	testl	%ecx,%ecx
28 ac0e2db6 2004-04-21 devnull 	jz	_sub1
29 ac0e2db6 2004-04-21 devnull 
30 ac0e2db6 2004-04-21 devnull 	/* diff[0:blen-1],borrow = a[0:blen-1] - b[0:blen-1] */
31 ac0e2db6 2004-04-21 devnull _subloop1:
32 ac0e2db6 2004-04-21 devnull 	movl	(%esi, %ebp, 4), %eax
33 ac0e2db6 2004-04-21 devnull 	sbbl	(%ebx, %ebp, 4), %eax
34 ac0e2db6 2004-04-21 devnull 	movl	%eax, (%edi, %ebp, 4)
35 ac0e2db6 2004-04-21 devnull 	incl	%ebp
36 ac0e2db6 2004-04-21 devnull 	loop	_subloop1
37 ac0e2db6 2004-04-21 devnull 
38 ac0e2db6 2004-04-21 devnull _sub1:
39 ac0e2db6 2004-04-21 devnull 	incl	%edx
40 ac0e2db6 2004-04-21 devnull 	movl	%edx,%ecx
41 ac0e2db6 2004-04-21 devnull 	loop	_subloop2
42 ac0e2db6 2004-04-21 devnull 	jmp done
43 ac0e2db6 2004-04-21 devnull 
44 ac0e2db6 2004-04-21 devnull 	/* diff[blen:alen-1] = a[blen:alen-1] - 0 */
45 ac0e2db6 2004-04-21 devnull _subloop2:
46 ac0e2db6 2004-04-21 devnull 	movl	(%esi, %ebp, 4), %eax
47 ac0e2db6 2004-04-21 devnull 	sbbl	$0, %eax
48 ac0e2db6 2004-04-21 devnull 	movl	%eax, (%edi, %ebp, 4)
49 ac0e2db6 2004-04-21 devnull 	INCL	%ebp
50 ac0e2db6 2004-04-21 devnull 	LOOP	_subloop2
51 ac0e2db6 2004-04-21 devnull 
52 ac0e2db6 2004-04-21 devnull done:
53 ac0e2db6 2004-04-21 devnull 	/* Postlude */
54 ac0e2db6 2004-04-21 devnull 	movl -4(%esp), %ebx		/* restore from stack */
55 ac0e2db6 2004-04-21 devnull 	movl -8(%esp), %esi
56 ac0e2db6 2004-04-21 devnull 	movl -12(%esp), %edi
57 ac0e2db6 2004-04-21 devnull 	movl %esp, %ebp
58 ac0e2db6 2004-04-21 devnull 	leave
59 ac0e2db6 2004-04-21 devnull 	ret
60 ac0e2db6 2004-04-21 devnull