/* Copyright (C) 1996, 1997, 2001, 2004 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson .
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include "div_libc.h"
#undef FRAME
#ifdef __alpha_fix__
#define FRAME 0
#else
#define FRAME 16
#endif
#undef X
#undef Y
#define X $17
#define Y $18
.set noat
.align 4
.globl ldiv
.ent ldiv
ldiv:
.frame sp, FRAME, ra
#if FRAME > 0
lda sp, -FRAME(sp)
#endif
#ifdef PROF
.set macro
ldgp gp, 0(pv)
lda AT, _mcount
jsr AT, (AT), _mcount
.set nomacro
.prologue 1
#else
.prologue 0
#endif
beq Y, $divbyzero
excb
mf_fpcr $f10
_ITOFT2 X, $f0, 0, Y, $f1, 8
.align 4
cvtqt $f0, $f0
cvtqt $f1, $f1
divt/c $f0, $f1, $f0
unop
/* Check to see if X fit in the double as an exact value. */
sll X, (64-53), AT
sra AT, (64-53), AT
cmpeq X, AT, AT
beq AT, $x_big
/* If we get here, we're expecting exact results from the division.
Do nothing else besides convert and clean up. */
cvttq/c $f0, $f0
excb
mt_fpcr $f10
_FTOIT $f0, $0, 0
$egress:
mulq $0, Y, $1
subq X, $1, $1
stq $0, 0($16)
stq $1, 8($16)
mov $16, $0
#if FRAME > 0
lda sp, FRAME(sp)
#endif
ret
.align 4
$x_big:
/* If we get here, X is large enough that we don't expect exact
results, and neither X nor Y got mis-translated for the fp
division. Our task is to take the fp result, figure out how
far it's off from the correct result and compute a fixup. */
#define Q v0 /* quotient */
#define R t0 /* remainder */
#define SY t1 /* scaled Y */
#define S t2 /* scalar */
#define QY t3 /* Q*Y */
/* The fixup code below can only handle unsigned values. */
or X, Y, AT
mov $31, t5
blt AT, $fix_sign_in
$fix_sign_in_ret1:
cvttq/c $f0, $f0
_FTOIT $f0, Q, 8
$fix_sign_in_ret2:
mulq Q, Y, QY
excb
mt_fpcr $f10
.align 4
subq QY, X, R
mov Y, SY
mov 1, S
bgt R, $q_high
$q_high_ret:
subq X, QY, R
mov Y, SY
mov 1, S
bgt R, $q_low
$q_low_ret:
negq Q, t4
cmovlbs t5, t4, Q
br $egress
.align 4
/* The quotient that we computed was too large. We need to reduce
it by S such that Y*S >= R. Obviously the closer we get to the
correct value the better, but overshooting high is ok, as we'll
fix that up later. */
0:
addq SY, SY, SY
addq S, S, S
$q_high:
cmpult SY, R, AT
bne AT, 0b
subq Q, S, Q
unop
subq QY, SY, QY
br $q_high_ret
.align 4
/* The quotient that we computed was too small. Divide Y by the
current remainder (R) and add that to the existing quotient (Q).
The expectation, of course, is that R is much smaller than X. */
/* Begin with a shift-up loop. Compute S such that Y*S >= R. We
already have a copy of Y in SY and the value 1 in S. */
0:
addq SY, SY, SY
addq S, S, S
$q_low:
cmpult SY, R, AT
bne AT, 0b
/* Shift-down and subtract loop. Each iteration compares our scaled
Y (SY) with the remainder (R); if SY <= R then X is divisible by
Y's scalar (S) so add it to the quotient (Q). */
2: addq Q, S, t3
srl S, 1, S
cmpule SY, R, AT
subq R, SY, t4
cmovne AT, t3, Q
cmovne AT, t4, R
srl SY, 1, SY
bne S, 2b
br $q_low_ret
.align 4
$fix_sign_in:
/* If we got here, then X|Y is negative. Need to adjust everything
such that we're doing unsigned division in the fixup loop. */
/* T5 is true if result should be negative. */
xor X, Y, AT
cmplt AT, 0, t5
cmplt X, 0, AT
negq X, t0
cmovne AT, t0, X
cmplt Y, 0, AT
negq Y, t0
cmovne AT, t0, Y
blbc t5, $fix_sign_in_ret1
cvttq/c $f0, $f0
_FTOIT $f0, Q, 8
.align 3
negq Q, Q
br $fix_sign_in_ret2
$divbyzero:
mov a0, v0
lda a0, GEN_INTDIV
call_pal PAL_gentrap
stq zero, 0(v0)
stq zero, 8(v0)
#if FRAME > 0
lda sp, FRAME(sp)
#endif
ret
.end ldiv