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|
@ libgcc routines for ARM cpu.
@ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk)
/* Copyright 1995, 1996, 1998, 1999, 2000 Free Software Foundation, Inc.
This file is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.
In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file. (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)
This file 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* ------------------------------------------------------------------------ */
/* We need to know what prefix to add to function names. */
#ifndef __USER_LABEL_PREFIX__
#error __USER_LABEL_PREFIX__ not defined
#endif
/* ANSI concatenation macros. */
#define CONCAT1(a, b) CONCAT2(a, b)
#define CONCAT2(a, b) a ## b
/* Use the right prefix for global labels. */
#define SYM(x) CONCAT1 (__USER_LABEL_PREFIX__, x)
#ifdef __ELF__
#ifdef __thumb__
#define __PLT__ /* Not supported in Thumb assembler (for now). */
#else
#define __PLT__ (PLT)
#endif
#define TYPE(x) .type SYM(x),function
#define SIZE(x) .size SYM(x), . - SYM(x)
#define LSYM(x) .x
#else
#define __PLT__
#define TYPE(x)
#define SIZE(x)
#define LSYM(x) x
#endif
/* Function end macros. Variants for 26 bit APCS and interworking. */
@ This selects the minimum architecture level required.
#define __ARM_ARCH__ 3
#if defined(__ARM_ARCH_3M__) || defined(__ARM_ARCH_4__) \
|| defined(__ARM_ARCH_4T__)
/* We use __ARM_ARCH__ set to 4 here, but in reality it's any processor with
long multiply instructions. That includes v3M. */
# undef __ARM_ARCH__
# define __ARM_ARCH__ 4
#endif
#if defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5T__) \
|| defined(__ARM_ARCH_5TE__)
# undef __ARM_ARCH__
# define __ARM_ARCH__ 5
#endif
/* How to return from a function call depends on the architecture variant. */
#ifdef __APCS_26__
# define RET movs pc, lr
# define RETc(x) mov##x##s pc, lr
#elif (__ARM_ARCH__ > 4) || defined(__ARM_ARCH_4T__)
# define RET bx lr
# define RETc(x) bx##x lr
# if (__ARM_ARCH__ == 4) \
&& (defined(__thumb__) || defined(__THUMB_INTERWORK__))
# define __INTERWORKING__
# endif
#else
# define RET mov pc, lr
# define RETc(x) mov##x pc, lr
#endif
/* Don't pass dirn, it's there just to get token pasting right. */
.macro RETLDM regs=, cond=, dirn=ia
#ifdef __APCS_26__
.ifc "\regs",""
ldm\cond\dirn sp!, {pc}^
.else
ldm\cond\dirn sp!, {\regs, pc}^
.endif
#elif defined (__INTERWORKING__)
.ifc "\regs",""
ldr\cond lr, [sp], #4
.else
ldm\cond\dirn sp!, {\regs, lr}
.endif
bx\cond lr
#else
.ifc "\regs",""
ldr\cond pc, [sp], #4
.else
ldm\cond\dirn sp!, {\regs, pc}
.endif
#endif
.endm
.macro ARM_LDIV0
LSYM(Ldiv0):
str lr, [sp, #-4]!
bl SYM (__div0) __PLT__
mov r0, #0 @ About as wrong as it could be.
RETLDM
.endm
.macro THUMB_LDIV0
LSYM(Ldiv0):
push { lr }
bl SYM (__div0)
mov r0, #0 @ About as wrong as it could be.
#if defined (__INTERWORKING__)
pop { r1 }
bx r1
#else
pop { pc }
#endif
.endm
.macro FUNC_END name
SIZE (__\name)
.endm
.macro DIV_FUNC_END name
LSYM(Ldiv0):
#ifdef __thumb__
THUMB_LDIV0
#else
ARM_LDIV0
#endif
FUNC_END \name
.endm
.macro THUMB_FUNC_START name
.globl SYM (\name)
TYPE (\name)
.thumb_func
SYM (\name):
.endm
/* Function start macros. Variants for ARM and Thumb. */
#ifdef __thumb__
#define THUMB_FUNC .thumb_func
#define THUMB_CODE .force_thumb
#else
#define THUMB_FUNC
#define THUMB_CODE
#endif
.macro FUNC_START name
.text
.globl SYM (__\name)
TYPE (__\name)
.align 0
THUMB_CODE
THUMB_FUNC
SYM (__\name):
.endm
/* Special function that will always be coded in ARM assembly, even if
in Thumb-only compilation. */
#if defined(__thumb__) && !defined(__THUMB_INTERWORK__)
.macro ARM_FUNC_START name
FUNC_START \name
bx pc
nop
.arm
_L__\name: /* A hook to tell gdb that we've switched to ARM */
.endm
#else
.macro ARM_FUNC_START name
FUNC_START \name
.endm
#endif
#ifdef __thumb__
/* Register aliases. */
work .req r4 @ XXXX is this safe ?
dividend .req r0
divisor .req r1
overdone .req r2
result .req r2
curbit .req r3
#endif
#if 0
ip .req r12
sp .req r13
lr .req r14
pc .req r15
#endif
/* ------------------------------------------------------------------------ */
/* Bodies of the division and modulo routines. */
/* ------------------------------------------------------------------------ */
.macro ARM_DIV_BODY dividend, divisor, result, curbit
#if __ARM_ARCH__ >= 5
clz \curbit, \divisor
clz \result, \dividend
sub \result, \curbit, \result
mov \curbit, #1
mov \divisor, \divisor, lsl \result
mov \curbit, \curbit, lsl \result
mov \result, #0
#else
@ Initially shift the divisor left 3 bits if possible,
@ set curbit accordingly. This allows for curbit to be located
@ at the left end of each 4 bit nibbles in the division loop
@ to save one loop in most cases.
tst \divisor, #0xe0000000
moveq \divisor, \divisor, lsl #3
moveq \curbit, #8
movne \curbit, #1
@ Unless the divisor is very big, shift it up in multiples of
@ four bits, since this is the amount of unwinding in the main
@ division loop. Continue shifting until the divisor is
@ larger than the dividend.
1: cmp \divisor, #0x10000000
cmplo \divisor, \dividend
movlo \divisor, \divisor, lsl #4
movlo \curbit, \curbit, lsl #4
blo 1b
@ For very big divisors, we must shift it a bit at a time, or
@ we will be in danger of overflowing.
1: cmp \divisor, #0x80000000
cmplo \divisor, \dividend
movlo \divisor, \divisor, lsl #1
movlo \curbit, \curbit, lsl #1
blo 1b
mov \result, #0
#endif
@ Division loop
1: cmp \dividend, \divisor
subhs \dividend, \dividend, \divisor
orrhs \result, \result, \curbit
cmp \dividend, \divisor, lsr #1
subhs \dividend, \dividend, \divisor, lsr #1
orrhs \result, \result, \curbit, lsr #1
cmp \dividend, \divisor, lsr #2
subhs \dividend, \dividend, \divisor, lsr #2
orrhs \result, \result, \curbit, lsr #2
cmp \dividend, \divisor, lsr #3
subhs \dividend, \dividend, \divisor, lsr #3
orrhs \result, \result, \curbit, lsr #3
cmp \dividend, #0 @ Early termination?
movnes \curbit, \curbit, lsr #4 @ No, any more bits to do?
movne \divisor, \divisor, lsr #4
bne 1b
.endm
/* ------------------------------------------------------------------------ */
.macro ARM_DIV2_ORDER divisor, order
#if __ARM_ARCH__ >= 5
clz \order, \divisor
rsb \order, \order, #31
#else
cmp \divisor, #(1 << 16)
movhs \divisor, \divisor, lsr #16
movhs \order, #16
movlo \order, #0
cmp \divisor, #(1 << 8)
movhs \divisor, \divisor, lsr #8
addhs \order, \order, #8
cmp \divisor, #(1 << 4)
movhs \divisor, \divisor, lsr #4
addhs \order, \order, #4
cmp \divisor, #(1 << 2)
addhi \order, \order, #3
addls \order, \order, \divisor, lsr #1
#endif
.endm
/* ------------------------------------------------------------------------ */
.macro ARM_MOD_BODY dividend, divisor, order, spare
#if __ARM_ARCH__ >= 5
clz \order, \divisor
clz \spare, \dividend
sub \order, \order, \spare
mov \divisor, \divisor, lsl \order
#else
mov \order, #0
@ Unless the divisor is very big, shift it up in multiples of
@ four bits, since this is the amount of unwinding in the main
@ division loop. Continue shifting until the divisor is
@ larger than the dividend.
1: cmp \divisor, #0x10000000
cmplo \divisor, \dividend
movlo \divisor, \divisor, lsl #4
addlo \order, \order, #4
blo 1b
@ For very big divisors, we must shift it a bit at a time, or
@ we will be in danger of overflowing.
1: cmp \divisor, #0x80000000
cmplo \divisor, \dividend
movlo \divisor, \divisor, lsl #1
addlo \order, \order, #1
blo 1b
#endif
@ Perform all needed substractions to keep only the reminder.
@ Do comparisons in batch of 4 first.
subs \order, \order, #3 @ yes, 3 is intended here
blt 2f
1: cmp \dividend, \divisor
subhs \dividend, \dividend, \divisor
cmp \dividend, \divisor, lsr #1
subhs \dividend, \dividend, \divisor, lsr #1
cmp \dividend, \divisor, lsr #2
subhs \dividend, \dividend, \divisor, lsr #2
cmp \dividend, \divisor, lsr #3
subhs \dividend, \dividend, \divisor, lsr #3
cmp \dividend, #1
mov \divisor, \divisor, lsr #4
subges \order, \order, #4
bge 1b
tst \order, #3
teqne \dividend, #0
beq 5f
@ Either 1, 2 or 3 comparison/substractions are left.
2: cmn \order, #2
blt 4f
beq 3f
cmp \dividend, \divisor
subhs \dividend, \dividend, \divisor
mov \divisor, \divisor, lsr #1
3: cmp \dividend, \divisor
subhs \dividend, \dividend, \divisor
mov \divisor, \divisor, lsr #1
4: cmp \dividend, \divisor
subhs \dividend, \dividend, \divisor
5:
.endm
/* ------------------------------------------------------------------------ */
.macro THUMB_DIV_MOD_BODY modulo
@ Load the constant 0x10000000 into our work register.
mov work, #1
lsl work, #28
LSYM(Loop1):
@ Unless the divisor is very big, shift it up in multiples of
@ four bits, since this is the amount of unwinding in the main
@ division loop. Continue shifting until the divisor is
@ larger than the dividend.
cmp divisor, work
bhs LSYM(Lbignum)
cmp divisor, dividend
bhs LSYM(Lbignum)
lsl divisor, #4
lsl curbit, #4
b LSYM(Loop1)
LSYM(Lbignum):
@ Set work to 0x80000000
lsl work, #3
LSYM(Loop2):
@ For very big divisors, we must shift it a bit at a time, or
@ we will be in danger of overflowing.
cmp divisor, work
bhs LSYM(Loop3)
cmp divisor, dividend
bhs LSYM(Loop3)
lsl divisor, #1
lsl curbit, #1
b LSYM(Loop2)
LSYM(Loop3):
@ Test for possible subtractions ...
.if \modulo
@ ... On the final pass, this may subtract too much from the dividend,
@ so keep track of which subtractions are done, we can fix them up
@ afterwards.
mov overdone, #0
cmp dividend, divisor
blo LSYM(Lover1)
sub dividend, dividend, divisor
LSYM(Lover1):
lsr work, divisor, #1
cmp dividend, work
blo LSYM(Lover2)
sub dividend, dividend, work
mov ip, curbit
mov work, #1
ror curbit, work
orr overdone, curbit
mov curbit, ip
LSYM(Lover2):
lsr work, divisor, #2
cmp dividend, work
blo LSYM(Lover3)
sub dividend, dividend, work
mov ip, curbit
mov work, #2
ror curbit, work
orr overdone, curbit
mov curbit, ip
LSYM(Lover3):
lsr work, divisor, #3
cmp dividend, work
blo LSYM(Lover4)
sub dividend, dividend, work
mov ip, curbit
mov work, #3
ror curbit, work
orr overdone, curbit
mov curbit, ip
LSYM(Lover4):
mov ip, curbit
.else
@ ... and note which bits are done in the result. On the final pass,
@ this may subtract too much from the dividend, but the result will be ok,
@ since the "bit" will have been shifted out at the bottom.
cmp dividend, divisor
blo LSYM(Lover1)
sub dividend, dividend, divisor
orr result, result, curbit
LSYM(Lover1):
lsr work, divisor, #1
cmp dividend, work
blo LSYM(Lover2)
sub dividend, dividend, work
lsr work, curbit, #1
orr result, work
LSYM(Lover2):
lsr work, divisor, #2
cmp dividend, work
blo LSYM(Lover3)
sub dividend, dividend, work
lsr work, curbit, #2
orr result, work
LSYM(Lover3):
lsr work, divisor, #3
cmp dividend, work
blo LSYM(Lover4)
sub dividend, dividend, work
lsr work, curbit, #3
orr result, work
LSYM(Lover4):
.endif
cmp dividend, #0 @ Early termination?
beq LSYM(Lover5)
lsr curbit, #4 @ No, any more bits to do?
beq LSYM(Lover5)
lsr divisor, #4
b LSYM(Loop3)
LSYM(Lover5):
.if \modulo
@ Any subtractions that we should not have done will be recorded in
@ the top three bits of "overdone". Exactly which were not needed
@ are governed by the position of the bit, stored in ip.
mov work, #0xe
lsl work, #28
and overdone, work
beq LSYM(Lgot_result)
@ If we terminated early, because dividend became zero, then the
@ bit in ip will not be in the bottom nibble, and we should not
@ perform the additions below. We must test for this though
@ (rather relying upon the TSTs to prevent the additions) since
@ the bit in ip could be in the top two bits which might then match
@ with one of the smaller RORs.
mov curbit, ip
mov work, #0x7
tst curbit, work
beq LSYM(Lgot_result)
mov curbit, ip
mov work, #3
ror curbit, work
tst overdone, curbit
beq LSYM(Lover6)
lsr work, divisor, #3
add dividend, work
LSYM(Lover6):
mov curbit, ip
mov work, #2
ror curbit, work
tst overdone, curbit
beq LSYM(Lover7)
lsr work, divisor, #2
add dividend, work
LSYM(Lover7):
mov curbit, ip
mov work, #1
ror curbit, work
tst overdone, curbit
beq LSYM(Lgot_result)
lsr work, divisor, #1
add dividend, work
.endif
LSYM(Lgot_result):
.endm
/* ------------------------------------------------------------------------ */
/* Start of the Real Functions */
/* ------------------------------------------------------------------------ */
#ifdef L_udivsi3
FUNC_START udivsi3
#ifdef __thumb__
cmp divisor, #0
beq LSYM(Ldiv0)
mov curbit, #1
mov result, #0
push { work }
cmp dividend, divisor
blo LSYM(Lgot_result)
THUMB_DIV_MOD_BODY 0
mov r0, result
pop { work }
RET
#else /* ARM version. */
subs r2, r1, #1
RETc(eq)
bcc LSYM(Ldiv0)
cmp r0, r1
bls 11f
tst r1, r2
beq 12f
ARM_DIV_BODY r0, r1, r2, r3
mov r0, r2
RET
11: moveq r0, #1
movne r0, #0
RET
12: ARM_DIV2_ORDER r1, r2
mov r0, r0, lsr r2
RET
#endif /* ARM version */
DIV_FUNC_END udivsi3
#endif /* L_udivsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_umodsi3
FUNC_START umodsi3
#ifdef __thumb__
cmp divisor, #0
beq LSYM(Ldiv0)
mov curbit, #1
cmp dividend, divisor
bhs LSYM(Lover10)
RET
LSYM(Lover10):
push { work }
THUMB_DIV_MOD_BODY 1
pop { work }
RET
#else /* ARM version. */
subs r2, r1, #1 @ compare divisor with 1
bcc LSYM(Ldiv0)
cmpne r0, r1 @ compare dividend with divisor
moveq r0, #0
tsthi r1, r2 @ see if divisor is power of 2
andeq r0, r0, r2
RETc(ls)
ARM_MOD_BODY r0, r1, r2, r3
RET
#endif /* ARM version. */
DIV_FUNC_END umodsi3
#endif /* L_umodsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_divsi3
FUNC_START divsi3
#ifdef __thumb__
cmp divisor, #0
beq LSYM(Ldiv0)
push { work }
mov work, dividend
eor work, divisor @ Save the sign of the result.
mov ip, work
mov curbit, #1
mov result, #0
cmp divisor, #0
bpl LSYM(Lover10)
neg divisor, divisor @ Loops below use unsigned.
LSYM(Lover10):
cmp dividend, #0
bpl LSYM(Lover11)
neg dividend, dividend
LSYM(Lover11):
cmp dividend, divisor
blo LSYM(Lgot_result)
THUMB_DIV_MOD_BODY 0
mov r0, result
mov work, ip
cmp work, #0
bpl LSYM(Lover12)
neg r0, r0
LSYM(Lover12):
pop { work }
RET
#else /* ARM version. */
cmp r1, #0
eor ip, r0, r1 @ save the sign of the result.
beq LSYM(Ldiv0)
rsbmi r1, r1, #0 @ loops below use unsigned.
subs r2, r1, #1 @ division by 1 or -1 ?
beq 10f
movs r3, r0
rsbmi r3, r0, #0 @ positive dividend value
cmp r3, r1
bls 11f
tst r1, r2 @ divisor is power of 2 ?
beq 12f
ARM_DIV_BODY r3, r1, r0, r2
cmp ip, #0
rsbmi r0, r0, #0
RET
10: teq ip, r0 @ same sign ?
rsbmi r0, r0, #0
RET
11: movlo r0, #0
moveq r0, ip, asr #31
orreq r0, r0, #1
RET
12: ARM_DIV2_ORDER r1, r2
cmp ip, #0
mov r0, r3, lsr r2
rsbmi r0, r0, #0
RET
#endif /* ARM version */
DIV_FUNC_END divsi3
#endif /* L_divsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_modsi3
FUNC_START modsi3
#ifdef __thumb__
mov curbit, #1
cmp divisor, #0
beq LSYM(Ldiv0)
bpl LSYM(Lover10)
neg divisor, divisor @ Loops below use unsigned.
LSYM(Lover10):
push { work }
@ Need to save the sign of the dividend, unfortunately, we need
@ work later on. Must do this after saving the original value of
@ the work register, because we will pop this value off first.
push { dividend }
cmp dividend, #0
bpl LSYM(Lover11)
neg dividend, dividend
LSYM(Lover11):
cmp dividend, divisor
blo LSYM(Lgot_result)
THUMB_DIV_MOD_BODY 1
pop { work }
cmp work, #0
bpl LSYM(Lover12)
neg dividend, dividend
LSYM(Lover12):
pop { work }
RET
#else /* ARM version. */
cmp r1, #0
beq LSYM(Ldiv0)
rsbmi r1, r1, #0 @ loops below use unsigned.
movs ip, r0 @ preserve sign of dividend
rsbmi r0, r0, #0 @ if negative make positive
subs r2, r1, #1 @ compare divisor with 1
cmpne r0, r1 @ compare dividend with divisor
moveq r0, #0
tsthi r1, r2 @ see if divisor is power of 2
andeq r0, r0, r2
bls 10f
ARM_MOD_BODY r0, r1, r2, r3
10: cmp ip, #0
rsbmi r0, r0, #0
RET
#endif /* ARM version */
DIV_FUNC_END modsi3
#endif /* L_modsi3 */
/* ------------------------------------------------------------------------ */
#ifdef L_dvmd_tls
FUNC_START div0
RET
FUNC_END div0
#endif /* L_divmodsi_tools */
/* ------------------------------------------------------------------------ */
#ifdef L_dvmd_lnx
@ GNU/Linux division-by zero handler. Used in place of L_dvmd_tls
/* Constants taken from <asm/unistd.h> and <asm/signal.h> */
#define SIGFPE 8
#define __NR_SYSCALL_BASE 0x900000
#define __NR_getpid (__NR_SYSCALL_BASE+ 20)
#define __NR_kill (__NR_SYSCALL_BASE+ 37)
.code 32
FUNC_START div0
stmfd sp!, {r1, lr}
swi __NR_getpid
cmn r0, #1000
RETLDM r1 hs
mov r1, #SIGFPE
swi __NR_kill
RETLDM r1
FUNC_END div0
#endif /* L_dvmd_lnx */
/* ------------------------------------------------------------------------ */
/* These next two sections are here despite the fact that they contain Thumb
assembler because their presence allows interworked code to be linked even
when the GCC library is this one. */
/* Do not build the interworking functions when the target architecture does
not support Thumb instructions. (This can be a multilib option). */
#if defined L_call_via_rX && (defined __ARM_ARCH_4T__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__)
/* These labels & instructions are used by the Arm/Thumb interworking code.
The address of function to be called is loaded into a register and then
one of these labels is called via a BL instruction. This puts the
return address into the link register with the bottom bit set, and the
code here switches to the correct mode before executing the function. */
.text
.align 0
.force_thumb
.macro call_via register
THUMB_FUNC_START _call_via_\register
bx \register
nop
SIZE (_call_via_\register)
.endm
call_via r0
call_via r1
call_via r2
call_via r3
call_via r4
call_via r5
call_via r6
call_via r7
call_via r8
call_via r9
call_via sl
call_via fp
call_via ip
call_via sp
call_via lr
#endif /* L_call_via_rX */
/* ------------------------------------------------------------------------ */
/* Do not build the interworking functions when the target architecture does
not support Thumb instructions. (This can be a multilib option). */
#if defined L_interwork_call_via_rX && (defined __ARM_ARCH_4T__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__)
/* These labels & instructions are used by the Arm/Thumb interworking code,
when the target address is in an unknown instruction set. The address
of function to be called is loaded into a register and then one of these
labels is called via a BL instruction. This puts the return address
into the link register with the bottom bit set, and the code here
switches to the correct mode before executing the function. Unfortunately
the target code cannot be relied upon to return via a BX instruction, so
instead we have to store the resturn address on the stack and allow the
called function to return here instead. Upon return we recover the real
return address and use a BX to get back to Thumb mode. */
.text
.align 0
.code 32
.globl _arm_return
_arm_return:
RETLDM
.code 16
.macro interwork register
.code 16
THUMB_FUNC_START _interwork_call_via_\register
bx pc
nop
.code 32
.globl LSYM(Lchange_\register)
LSYM(Lchange_\register):
tst \register, #1
streq lr, [sp, #-4]!
adreq lr, _arm_return
bx \register
SIZE (_interwork_call_via_\register)
.endm
interwork r0
interwork r1
interwork r2
interwork r3
interwork r4
interwork r5
interwork r6
interwork r7
interwork r8
interwork r9
interwork sl
interwork fp
interwork ip
interwork sp
/* The LR case has to be handled a little differently... */
.code 16
THUMB_FUNC_START _interwork_call_via_lr
bx pc
nop
.code 32
.globl .Lchange_lr
.Lchange_lr:
tst lr, #1
stmeqdb r13!, {lr}
mov ip, lr
adreq lr, _arm_return
bx ip
SIZE (_interwork_call_via_lr)
#endif /* L_interwork_call_via_rX */
#include "ieee754-df.S"
#include "ieee754-sf.S"
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