minix/lib/libc/arch/alpha/gen/divrem.m4
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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/* $NetBSD: divrem.m4,v 1.9 2002/01/21 23:40:41 ross Exp $ */
/*
* Copyright (c) 1994, 1995 Carnegie-Mellon University.
* All rights reserved.
*
* Author: Chris G. Demetriou
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Division and remainder.
*
* The use of m4 is modeled after the sparc code, but the algorithm is
* simple binary long division.
*
* Note that the loops could probably benefit from unrolling.
*/
/*
* M4 Parameters
* NAME name of function to generate
* OP OP=div: t10 / t11 -> t12; OP=rem: t10 % t11 -> t12
* S S=true: signed; S=false: unsigned
* WORDSIZE total number of bits
*/
define(A, `t10')
define(B, `t11')
define(RESULT, `t12')
define(BIT, `t0')
define(I, `t1')
define(CC, `t2')
define(T_0, `t3')
ifelse(S, `true', `define(NEG, `t4')')
#include <machine/asm.h>
LEAF(NAME, 0) /* XXX */
lda sp, -64(sp)
stq BIT, 0(sp)
stq I, 8(sp)
stq CC, 16(sp)
stq T_0, 24(sp)
ifelse(S, `true',
` stq NEG, 32(sp)')
stq A, 40(sp)
stq B, 48(sp)
mov zero, RESULT /* Initialize result to zero */
ifelse(S, `true',
`
/* Compute sign of result. If either is negative, this is easy. */
or A, B, NEG /* not the sign, but... */
srl NEG, WORDSIZE - 1, NEG /* rather, or of high bits */
blbc NEG, Ldoit /* neither negative? do it! */
ifelse(OP, `div',
` xor A, B, NEG /* THIS is the sign! */
', ` mov A, NEG /* sign follows A. */
')
srl NEG, WORDSIZE - 1, NEG /* make negation the low bit. */
srl A, WORDSIZE - 1, I /* is A negative? */
blbc I, LnegB /* no. */
/* A is negative; flip it. */
ifelse(WORDSIZE, `32', `
/* top 32 bits may be random junk */
zap A, 0xf0, A
')
subq zero, A, A
srl B, WORDSIZE - 1, I /* is B negative? */
blbc I, Ldoit /* no. */
LnegB:
/* B is definitely negative, no matter how we got here. */
ifelse(WORDSIZE, `32', `
/* top 32 bits may be random junk */
zap B, 0xf0, B
')
subq zero, B, B
Ldoit:
')
ifelse(WORDSIZE, `32', `
/*
* Clear the top 32 bits of each operand, as they may
* sign extension (if negated above), or random junk.
*/
zap A, 0xf0, A
zap B, 0xf0, B
')
/* kill the special cases. */
beq B, Ldotrap /* division by zero! */
cmpult A, B, CC /* A < B? */
/* RESULT is already zero, from above. A is untouched. */
bne CC, Lret_result
cmpeq A, B, CC /* A == B? */
cmovne CC, 1, RESULT
cmovne CC, zero, A
bne CC, Lret_result
/*
* Find out how many bits of zeros are at the beginning of the divisor.
*/
LBbits:
ldiq T_0, 1 /* I = 0; BIT = 1<<WORDSIZE-1 */
mov zero, I
sll T_0, WORDSIZE-1, BIT
LBloop:
and B, BIT, CC /* if bit in B is set, done. */
bne CC, LAbits
addq I, 1, I /* increment I, shift bit */
srl BIT, 1, BIT
cmplt I, WORDSIZE-1, CC /* if I leaves one bit, done. */
bne CC, LBloop
LAbits:
beq I, Ldodiv /* If I = 0, divide now. */
ldiq T_0, 1 /* BIT = 1<<WORDSIZE-1 */
sll T_0, WORDSIZE-1, BIT
LAloop:
and A, BIT, CC /* if bit in A is set, done. */
bne CC, Ldodiv
subq I, 1, I /* decrement I, shift bit */
srl BIT, 1, BIT
bne I, LAloop /* If I != 0, loop again */
Ldodiv:
sll B, I, B /* B <<= i */
ldiq T_0, 1
sll T_0, I, BIT
Ldivloop:
cmpult A, B, CC
or RESULT, BIT, T_0
cmoveq CC, T_0, RESULT
subq A, B, T_0
cmoveq CC, T_0, A
srl BIT, 1, BIT
srl B, 1, B
beq A, Lret_result
bne BIT, Ldivloop
Lret_result:
ifelse(OP, `div',
`', ` mov A, RESULT
')
ifelse(S, `true',
`
/* Check to see if we should negate it. */
subq zero, RESULT, T_0
cmovlbs NEG, T_0, RESULT
')
ldq BIT, 0(sp)
ldq I, 8(sp)
ldq CC, 16(sp)
ldq T_0, 24(sp)
ifelse(S, `true',
` ldq NEG, 32(sp)')
ldq A, 40(sp)
ldq B, 48(sp)
lda sp, 64(sp)
ret zero, (t9), 1
Ldotrap:
ldiq a0, -2 /* This is the signal to SIGFPE! */
call_pal PAL_gentrap
ifelse(OP, `div',
`', ` mov zero, A /* so that zero will be returned */
')
br zero, Lret_result
END(NAME)