/*
* lbn68020.c - 32-bit bignum primitives for the 68020+ (0r 683xx) processors.
*
* Copyright (c) 1995 Colin Plumb. All rights reserved.
* For licensing and other legal details, see the file legal.c.
*
* This was written for Metrowerks C, and while it should be reasonably
* portable, NOTE that Metrowerks lets a callee trash a0, a1, d0, d1, and d2.
* Some 680x0 compilers make d2 callee-save, so instructions to save it
* will have to be added.
*
* This code supports 16 or 32-bit ints, based on UINT_MAX.
* Regardless of UINT_MAX, only bignums up to 64K words (2 million bits)
* are supported. (68k hackers will recognize this as a consequence of
* using dbra.)
*
* These primitives use little-endian word order.
* (The order of bytes within words is irrelevant to this issue.)
*
* TODO: Schedule this for the 68040's pipeline. (When I get a 68040 manual.)
*/
#include <limits.h>
#include "lbn.h" /* Should include lbn68020.h */
/*
* The Metrowerks C compiler (1.2.2) produces bad 68k code for the
* following input, which happens to be the inner loop of lbnSub1,
* so a few less than critical routines have been recoded in assembly
* to avoid the bug. (Optimizer on or off does not matter.)
*
* unsigned
* decrement(unsigned *num, unsigned len)
* {
* do {
* if ((*num++)-- != 0)
* return 0;
* } while (--len);
* return 1;
* }
*/
asm BNWORD32
lbnSub1_32(BNWORD32 *num, unsigned len, BNWORD32 borrow)
{
movea.l 4(sp),a0 /* num */
#if UINT_MAX == 0xffff
move.l 10(sp),d0 /* borrow */
#else
move.l 12(sp),d0 /* borrow */
#endif
sub.l d0,(a0)+
bcc done
#if UINT_MAX == 0xffff
move.w 8(sp),d0 /* len */
#else
move.w 10(sp),d0 /* len */
#endif
subq.w #2,d0
bcs done
loop:
subq.l #1,(a0)+
dbcc d0,loop
done:
moveq.l #0,d0
addx.w d0,d0
rts
}
asm BNWORD32
lbnAdd1_32(BNWORD32 *num, unsigned len, BNWORD32 carry)
{
movea.l 4(sp),a0 /* num */
#if UINT_MAX == 0xffff
move.l 10(sp),d0 /* carry */
#else
move.l 12(sp),d0 /* carry */
#endif
add.l d0,(a0)+
bcc done
#if UINT_MAX == 0xffff
move.w 8(sp),d0 /* len */
#else
move.w 10(sp),d0 /* len */
#endif
subq.w #2,d0
bcs done
loop:
addq.l #1,(a0)+
dbcc d0,loop
done:
moveq.l #0,d0
addx.w d0,d0
rts
}
asm void
lbnMulN1_32(BNWORD32 *out, BNWORD32 const *in, unsigned len, BNWORD32 k)
{
machine 68020
movem.l d3-d5,-(sp) /* 12 bytes of extra data */
moveq.l #0,d4
move.l 16(sp),a1 /* out */
move.l 20(sp),a0 /* in */
#if UINT_MAX == 0xffff
move.w 24(sp),d5 /* len */
move.l 26(sp),d2 /* k */
#else
move.w 26(sp),d5 /* len */
move.l 28(sp),d2 /* k */
#endif
move.l (a0)+,d3 /* First multiply */
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
move.l d3,(a1)+
subq.w #1,d5 /* Setup for loop unrolling */
lsr.w #1,d5
bcs.s m32_even
beq.s m32_short
subq.w #1,d5 /* Set up software pipeline properly */
move.l d1,d0
m32_loop:
move.l (a0)+,d3
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
add.l d0,d3
addx.l d4,d1
move.l d3,(a1)+
m32_even:
move.l (a0)+,d3
mulu.l d2,d0:d3 /* dc.w 0x4c02, 0x3400 */
add.l d1,d3
addx.l d4,d0
move.l d3,(a1)+
dbra d5,m32_loop
move.l d0,(a1)
movem.l (sp)+,d3-d5
rts
m32_short:
move.l d1,(a1)
movem.l (sp)+,d3-d5
rts
}
asm BNWORD32
lbnMulAdd1_32(BNWORD32 *out, BNWORD32 const *in, unsigned len, BNWORD32 k)
{
machine 68020
movem.l d3-d5,-(sp) /* 12 bytes of extra data */
moveq.l #0,d4
move.l 16(sp),a1 /* out */
move.l 20(sp),a0 /* in */
#if UINT_MAX == 0xffff
move.w 24(sp),d5 /* len */
move.l 26(sp),d2 /* k */
#else
move.w 26(sp),d5 /* len */
move.l 28(sp),d2 /* k */
#endif
move.l (a0)+,d3 /* First multiply */
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
add.l d3,(a1)+
addx.l d4,d1
subq.w #1,d5 /* Setup for loop unrolling */
lsr.w #1,d5
bcs.s ma32_even
beq.s ma32_short
subq.w #1,d5 /* Set up software pipeline properly */
move.l d1,d0
ma32_loop:
move.l (a0)+,d3
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
add.l d0,d3
addx.l d4,d1
add.l d3,(a1)+
addx.l d4,d1
ma32_even:
move.l (a0)+,d3
mulu.l d2,d0:d3 /* dc.w 0x4c02, 0x3400 */
add.l d1,d3
addx.l d4,d0
add.l d3,(a1)+
addx.l d4,d0
dbra d5,ma32_loop
movem.l (sp)+,d3-d5
rts
ma32_short:
move.l d1,d0
movem.l (sp)+,d3-d5
rts
}
asm BNWORD32
lbnMulSub1_32(BNWORD32 *out, BNWORD32 const *in, unsigned len, BNWORD32 k)
{
machine 68020
movem.l d3-d5,-(sp) /* 12 bytes of extra data */
moveq.l #0,d4
move.l 16(sp),a1 /* out */
move.l 20(sp),a0 /* in */
#if UINT_MAX == 0xffff
move.w 24(sp),d5 /* len */
move.l 26(sp),d2 /* k */
#else
move.w 26(sp),d5 /* len */
move.l 28(sp),d2 /* k */
#endif
move.l (a0)+,d3 /* First multiply */
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
sub.l d3,(a1)+
addx.l d4,d1
subq.w #1,d5 /* Setup for loop unrolling */
lsr.w #1,d5
bcs.s ms32_even
beq.s ms32_short
subq.w #1,d5 /* Set up software pipeline properly */
move.l d1,d0
ms32_loop:
move.l (a0)+,d3
mulu.l d2,d1:d3 /* dc.w 0x4c02, 0x3401 */
add.l d0,d3
addx.l d4,d1
sub.l d3,(a1)+
addx.l d4,d1
ms32_even:
move.l (a0)+,d3
mulu.l d2,d0:d3 /* dc.w 0x4c02, 0x3400 */
add.l d1,d3
addx.l d4,d0
sub.l d3,(a1)+
addx.l d4,d0
dbra d5,ms32_loop
movem.l (sp)+,d3-d5
rts
ms32_short:
move.l d1,d0
movem.l (sp)+,d3-d5
rts
}
asm BNWORD32
lbnDiv21_32(BNWORD32 *q, BNWORD32 nh, BNWORD32 nl, BNWORD32 d)
{
machine 68020
move.l 8(sp),d0
move.l 12(sp),d1
move.l 4(sp),a0
divu.l 16(sp),d0:d1 /* dc.w 0x4c6f, 0x1400, 16 */
move.l d1,(a0)
rts
}
asm unsigned
lbnModQ_32(BNWORD32 const *n, unsigned len, unsigned d)
{
machine 68020
move.l 4(sp),a0 /* n */
move.l d3,a1
#if UINT_MAX == 0xffff
moveq.l #0,d2
move.w 8(sp),d1 /* len */
move.w 10(sp),d2 /* d */
#else
move.w 10(sp),d1 /* len */
move.l 12(sp),d2 /* d */
#endif
dc.w 0x41f0, 0x1cfc /* lea -4(a0,d1.L*4),a0 */
/* First time, divide 32/32 - may be faster than 64/32 */
move.l (a0),d3
divul.l d2,d0:d3 /* dc.w 0x4c02, 0x3000 */
subq.w #2,d1
bmi mq32_done
mq32_loop:
move.l -(a0),d3
divu.l d2,d0:d3 /* dc.w 0x4c02,0x3400 */
dbra d1,mq32_loop
mq32_done:
move.l a1,d3
rts
}
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