1 4e3a81b9 2006-04-21 devnull /*	mpvecadd(mpdigit *a, int alen, mpdigit *b, int blen, mpdigit *sum) */
 2 4e3a81b9 2006-04-21 devnull /*		sum[0:alen] = a[0:alen-1] + b[0:blen-1] */
 3 4e3a81b9 2006-04-21 devnull /*	prereq: alen >= blen, sum has room for alen+1 digits */
 4 4e3a81b9 2006-04-21 devnull /* (very old gnu assembler doesn't allow multiline comments) */
 5 4e3a81b9 2006-04-21 devnull 
 6 4e3a81b9 2006-04-21 devnull .text
 7 4e3a81b9 2006-04-21 devnull 
 8 4e3a81b9 2006-04-21 devnull .p2align 2,0x90
 9 4e3a81b9 2006-04-21 devnull .globl _mpvecadd
10 4e3a81b9 2006-04-21 devnull _mpvecadd:
11 4e3a81b9 2006-04-21 devnull 	/* Prelude */
12 4e3a81b9 2006-04-21 devnull 	pushl %ebp		/* save on stack */
13 4e3a81b9 2006-04-21 devnull 	pushl %ebx
14 4e3a81b9 2006-04-21 devnull 	pushl %esi
15 4e3a81b9 2006-04-21 devnull 	pushl %edi
16 4e3a81b9 2006-04-21 devnull 
17 4e3a81b9 2006-04-21 devnull 	leal 20(%esp), %ebp		/* %ebp = FP for now */
18 4e3a81b9 2006-04-21 devnull 
19 4e3a81b9 2006-04-21 devnull 	movl	4(%ebp), %edx		/* alen */
20 4e3a81b9 2006-04-21 devnull 	movl	12(%ebp), %ecx		/* blen */
21 4e3a81b9 2006-04-21 devnull 	movl	0(%ebp), %esi		/* a */
22 4e3a81b9 2006-04-21 devnull 	movl	8(%ebp), %ebx		/* b */
23 4e3a81b9 2006-04-21 devnull 	subl	%ecx, %edx
24 4e3a81b9 2006-04-21 devnull 	movl	16(%ebp), %edi		/* sum */
25 4e3a81b9 2006-04-21 devnull 	xorl	%ebp, %ebp		/* this also sets carry to 0 */
26 4e3a81b9 2006-04-21 devnull 
27 4e3a81b9 2006-04-21 devnull 	/* skip addition if b is zero */
28 4e3a81b9 2006-04-21 devnull 	testl	%ecx,%ecx
29 4e3a81b9 2006-04-21 devnull 	je	_add1
30 4e3a81b9 2006-04-21 devnull 
31 4e3a81b9 2006-04-21 devnull 	/* sum[0:blen-1],carry = a[0:blen-1] + b[0:blen-1] */
32 4e3a81b9 2006-04-21 devnull _addloop1:
33 4e3a81b9 2006-04-21 devnull 	movl	(%esi, %ebp, 4), %eax
34 4e3a81b9 2006-04-21 devnull 	adcl	(%ebx, %ebp, 4), %eax
35 4e3a81b9 2006-04-21 devnull 	movl	%eax, (%edi, %ebp, 4)
36 4e3a81b9 2006-04-21 devnull 	incl	%ebp
37 4e3a81b9 2006-04-21 devnull 	loop	_addloop1
38 4e3a81b9 2006-04-21 devnull 
39 4e3a81b9 2006-04-21 devnull _add1:
40 4e3a81b9 2006-04-21 devnull 	/* jump if alen > blen */
41 4e3a81b9 2006-04-21 devnull 	incl	%edx
42 4e3a81b9 2006-04-21 devnull 	movl	%edx, %ecx
43 4e3a81b9 2006-04-21 devnull 	loop	_addloop2
44 4e3a81b9 2006-04-21 devnull 
45 4e3a81b9 2006-04-21 devnull 	/* sum[alen] = carry */
46 4e3a81b9 2006-04-21 devnull _addend:
47 4e3a81b9 2006-04-21 devnull 	jb	_addcarry
48 4e3a81b9 2006-04-21 devnull 	movl	$0, (%edi, %ebp, 4)
49 4e3a81b9 2006-04-21 devnull 	jmp done
50 4e3a81b9 2006-04-21 devnull 
51 4e3a81b9 2006-04-21 devnull _addcarry:
52 4e3a81b9 2006-04-21 devnull 	movl	$1, (%edi, %ebp, 4)
53 4e3a81b9 2006-04-21 devnull 	jmp done
54 4e3a81b9 2006-04-21 devnull 
55 4e3a81b9 2006-04-21 devnull 	/* sum[blen:alen-1],carry = a[blen:alen-1] + 0 */
56 4e3a81b9 2006-04-21 devnull _addloop2:
57 4e3a81b9 2006-04-21 devnull 	movl	(%esi, %ebp, 4),%eax
58 4e3a81b9 2006-04-21 devnull 	adcl	$0, %eax
59 4e3a81b9 2006-04-21 devnull 	movl	%eax, (%edi, %ebp, 4)
60 4e3a81b9 2006-04-21 devnull 	incl	%ebp
61 4e3a81b9 2006-04-21 devnull 	loop	_addloop2
62 4e3a81b9 2006-04-21 devnull 	jmp	_addend
63 4e3a81b9 2006-04-21 devnull 
64 4e3a81b9 2006-04-21 devnull done:
65 4e3a81b9 2006-04-21 devnull 	/* Postlude */
66 4e3a81b9 2006-04-21 devnull 	popl %edi
67 4e3a81b9 2006-04-21 devnull 	popl %esi
68 4e3a81b9 2006-04-21 devnull 	popl %ebx
69 4e3a81b9 2006-04-21 devnull 	popl %ebp
70 4e3a81b9 2006-04-21 devnull 	ret