mirror of
https://github.com/vivier/EMILE.git
synced 2024-12-23 01:29:34 +00:00
59 lines
1.8 KiB
ArmAsm
59 lines
1.8 KiB
ArmAsm
/*
|
|
*
|
|
* (c) 2004,2005 Laurent Vivier <LaurentVivier@wanadoo.fr>
|
|
*
|
|
* Some parts from libgcc routines for 68000 w/o floating-point hardware.
|
|
* Copyright (C) 1994, 1996, 1997, 1998 Free Software Foundation, Inc.
|
|
*
|
|
*/
|
|
|
|
.chip 68000
|
|
|
|
.align 2
|
|
|
|
.globl __udivsi3
|
|
__udivsi3:
|
|
movel %d2, %sp@-
|
|
movel %sp@(12), %d1 /* %d1 = divisor */
|
|
movel %sp@(8), %d0 /* %d0 = dividend */
|
|
|
|
cmpl #0x10000, %d1 /* divisor >= 2 ^ 16 ? */
|
|
jcc __udivsi3L3 /* then try next algorithm */
|
|
movel %d0, %d2
|
|
clrw %d2
|
|
swap %d2
|
|
divu %d1, %d2 /* high quotient in lower word */
|
|
movew %d2, %d0 /* save high quotient */
|
|
swap %d0
|
|
movew %sp@(10), %d2 /* get low dividend + high rest */
|
|
divu %d1, %d2 /* low quotient */
|
|
movew %d2, %d0
|
|
jra __udivsi3L6
|
|
|
|
__udivsi3L3: movel %d1, %d2 /* use %d2 as divisor backup */
|
|
__udivsi3L4: lsrl #1, %d1 /* shift divisor */
|
|
lsrl #1, %d0 /* shift dividend */
|
|
cmpl #0x10000, %d1 /* still divisor >= 2 ^ 16 ? */
|
|
jcc __udivsi3L4
|
|
divu %d1, %d0 /* now we have 16-bit divisor */
|
|
andl #0xffff, %d0 /* mask out divisor, ignore remainder */
|
|
|
|
/* Multiply the 16-bit tentative quotient with the 32-bit divisor. Because of
|
|
the operand ranges, this might give a 33-bit product. If this product is
|
|
greater than the dividend, the tentative quotient was too large. */
|
|
movel %d2, %d1
|
|
mulu %d0, %d1 /* low part, 32 bits */
|
|
swap %d2
|
|
mulu %d0, %d2 /* high part, at most 17 bits */
|
|
swap %d2 /* align high part with low part */
|
|
tstw %d2 /* high part 17 bits? */
|
|
jne __udivsi3L5 /* if 17 bits, quotient was too large */
|
|
addl %d2, %d1 /* add parts */
|
|
jcs __udivsi3L5 /* if sum is 33 bits, quotient was too large */
|
|
cmpl %sp@(8), %d1 /* compare the sum with the dividend */
|
|
jls __udivsi3L6 /* if sum > dividend, quotient was too large */
|
|
__udivsi3L5: subql #1, %d0 /* adjust quotient */
|
|
|
|
__udivsi3L6: movel %sp@+, %d2
|
|
rts
|