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reactos/sdk/lib/crt/math/i386/pow_asm.s

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ArmAsm
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/* ix87 specific implementation of pow function.
Copyright (C) 1996, 1997, 1998, 1999, 2001, 2004, 2005, 2007
Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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. */
/* ReactOS modifications */
#include <asm.inc>
#define ALIGNARG(log2) log2
#define ASM_TYPE_DIRECTIVE(name,typearg)
#define ASM_SIZE_DIRECTIVE(name)
#define cfi_adjust_cfa_offset(x)
PUBLIC _pow
.data
ASSUME cs:nothing
.align ALIGNARG(4)
ASM_TYPE_DIRECTIVE(infinity,@object)
inf_zero:
infinity:
.byte 0, 0, 0, 0, 0, 0, HEX(f0), HEX(7f)
ASM_SIZE_DIRECTIVE(infinity)
ASM_TYPE_DIRECTIVE(zero,@object)
zero:
.double 0.0
ASM_SIZE_DIRECTIVE(zero)
ASM_TYPE_DIRECTIVE(minf_mzero,@object)
minf_mzero:
minfinity:
.byte 0, 0, 0, 0, 0, 0, HEX(f0), HEX(ff)
mzero:
.byte 0, 0, 0, 0, 0, 0, 0, HEX(80)
ASM_SIZE_DIRECTIVE(minf_mzero)
ASM_TYPE_DIRECTIVE(one,@object)
one:
.double 1.0
ASM_SIZE_DIRECTIVE(one)
ASM_TYPE_DIRECTIVE(limit,@object)
limit:
.double 0.29
ASM_SIZE_DIRECTIVE(limit)
ASM_TYPE_DIRECTIVE(p63,@object)
p63:
.byte 0, 0, 0, 0, 0, 0, HEX(e0), HEX(43)
ASM_SIZE_DIRECTIVE(p63)
#ifdef PIC
#define MO(op) op##@GOTOFF(%ecx)
#define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
#else
#define MO(op) op
#define MOX(op,x,f) op[x*f]
#endif
.code
_pow:
fld qword ptr [esp + 12] // y
fxam
#ifdef PIC
LOAD_PIC_REG (cx)
#endif
fnstsw ax
mov dl, ah
and ah, HEX(045)
cmp ah, HEX(040) // is y == 0 ?
je L11
cmp ah, 5 // is y == <EFBFBD>inf ?
je L12
cmp ah, 1 // is y == NaN ?
je L30
fld qword ptr [esp + 4] // x : y
sub esp, 8
cfi_adjust_cfa_offset (8)
fxam
fnstsw ax
mov dh, ah
and ah, HEX(45)
cmp ah, HEX(040)
je L20 // x is <EFBFBD>0
cmp ah, 5
je L15 // x is <EFBFBD>inf
fxch st(1) // y : x
/* fistpll raises invalid exception for |y| >= 1L<<63. */
fld st // y : y : x
fabs // |y| : y : x
fcomp qword ptr ds:MO(p63) // y : x
fnstsw ax
sahf
jnc L2
/* First see whether `y' is a natural number. In this case we
can use a more precise algorithm. */
fld st // y : y : x
fistp qword ptr [esp] // y : x
fild qword ptr [esp] // int(y) : y : x
fucomp st(1) // y : x
fnstsw ax
sahf
jne L2
/* OK, we have an integer value for y. */
pop eax
cfi_adjust_cfa_offset (-4)
pop edx
cfi_adjust_cfa_offset (-4)
or edx, 0
fstp st // x
jns L4 // y >= 0, jump
fdivr qword ptr MO(one) // 1/x (now referred to as x)
neg eax
adc edx, 0
neg edx
L4: fld qword ptr MO(one) // 1 : x
fxch st(1)
L6: shrd eax, edx, 1
jnc L5
fxch st(1)
fmul st, st(1) // x : ST*x
fxch st(1)
L5: fmul st, st // x*x : ST*x
shr edx, 1
mov ecx, eax
or ecx, edx
jnz L6
fstp st // ST*x
ret
/* y is <20>NAN */
L30:
fld qword ptr [esp + 4] // x : y
fld qword ptr MO(one) // 1.0 : x : y
fucomp st(1) // x : y
fnstsw ax
sahf
je L31
fxch st(1) // y : x
L31:fstp st(1)
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
L2: /* y is a real number. */
fxch st(1) // x : y
fld qword ptr MO(one) // 1.0 : x : y
fld qword ptr MO(limit) // 0.29 : 1.0 : x : y
fld st(2) // x : 0.29 : 1.0 : x : y
fsub st, st(2) // x-1 : 0.29 : 1.0 : x : y
fabs // |x-1| : 0.29 : 1.0 : x : y
fucompp // 1.0 : x : y
fnstsw ax
fxch st(1) // x : 1.0 : y
sahf
ja L7
fsub st, st(1) // x-1 : 1.0 : y
fyl2xp1 // log2(x) : y
jmp L8
L7: fyl2x // log2(x) : y
L8: fmul st, st(1) // y*log2(x) : y
fst st(1) // y*log2(x) : y*log2(x)
frndint // int(y*log2(x)) : y*log2(x)
fsub st(1), st // int(y*log2(x)) : fract(y*log2(x))
fxch // fract(y*log2(x)) : int(y*log2(x))
f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
fadd qword ptr MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
add esp, 8
cfi_adjust_cfa_offset (-8)
fstp st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
ret
// pow(x,<EFBFBD>0) = 1
.align ALIGNARG(4)
L11:fstp st(0) // pop y
fld qword ptr MO(one)
ret
// y == <EFBFBD>inf
.align ALIGNARG(4)
L12: fstp st(0) // pop y
fld qword ptr MO(one) // 1
fld qword ptr [esp + 4] // x : 1
fabs // abs(x) : 1
fucompp // < 1, == 1, or > 1
fnstsw ax
and ah, HEX(45)
cmp ah, HEX(45)
je L13 // jump if x is NaN
cmp ah, HEX(40)
je L14 // jump if |x| == 1
shl ah, 1
xor dl, ah
and edx, 2
fld qword ptr MOX(inf_zero, edx, 4)
ret
.align ALIGNARG(4)
L14:fld qword ptr MO(one)
ret
.align ALIGNARG(4)
L13:fld qword ptr [esp + 4] // load x == NaN
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
// x is <EFBFBD>inf
L15: fstp st(0) // y
test dh, 2
jz L16 // jump if x == +inf
// We must find out whether y is an odd integer.
fld st // y : y
fistp qword ptr [esp] // y
fild qword ptr [esp] // int(y) : y
fucompp // <empty>
fnstsw ax
sahf
jne L17
// OK, the value is an integer, but is the number of bits small
// enough so that all are coming from the mantissa?
pop eax
cfi_adjust_cfa_offset (-4)
pop edx
cfi_adjust_cfa_offset (-4)
and al, 1
jz L18 // jump if not odd
mov eax, edx
or edx, edx
jns L155
neg eax
L155:
cmp eax, HEX(000200000)
ja L18 // does not fit in mantissa bits
// It's an odd integer.
shr edx, 31
fld qword ptr MOX(minf_mzero, edx, 8)
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
L16:fcomp qword ptr ds:MO(zero)
add esp, 8
cfi_adjust_cfa_offset (-8)
fnstsw ax
shr eax, 5
and eax, 8
fld qword ptr MOX(inf_zero, eax, 1)
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
L17: shl edx, 30 // sign bit for y in right position
add esp, 8
cfi_adjust_cfa_offset (-8)
L18: shr edx, 31
fld qword ptr MOX(inf_zero, edx, 8)
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
// x is <EFBFBD>0
L20: fstp st(0) // y
test dl, 2
jz L21 // y > 0
// x is <EFBFBD>0 and y is < 0. We must find out whether y is an odd integer.
test dh, 2
jz L25
fld st // y : y
fistp qword ptr [esp] // y
fild qword ptr [esp] // int(y) : y
fucompp // <empty>
fnstsw ax
sahf
jne L26
// OK, the value is an integer, but is the number of bits small
// enough so that all are coming from the mantissa?
pop eax
cfi_adjust_cfa_offset (-4)
pop edx
cfi_adjust_cfa_offset (-4)
and al, 1
jz L27 // jump if not odd
cmp edx, HEX(0ffe00000)
jbe L27 // does not fit in mantissa bits
// It's an odd integer.
// Raise divide-by-zero exception and get minus infinity value.
fld qword ptr MO(one)
fdiv qword ptr MO(zero)
fchs
ret
cfi_adjust_cfa_offset (8)
L25: fstp st(0)
L26: add esp, 8
cfi_adjust_cfa_offset (-8)
L27: // Raise divide-by-zero exception and get infinity value.
fld qword ptr MO(one)
fdiv qword ptr MO(zero)
ret
cfi_adjust_cfa_offset (8)
.align ALIGNARG(4)
// x is <EFBFBD>0 and y is > 0. We must find out whether y is an odd integer.
L21:test dh, 2
jz L22
fld st // y : y
fistp qword ptr [esp] // y
fild qword ptr [esp] // int(y) : y
fucompp // <empty>
fnstsw ax
sahf
jne L23
// OK, the value is an integer, but is the number of bits small
// enough so that all are coming from the mantissa?
pop eax
cfi_adjust_cfa_offset (-4)
pop edx
cfi_adjust_cfa_offset (-4)
and al, 1
jz L24 // jump if not odd
cmp edx, HEX(0ffe00000)
jae L24 // does not fit in mantissa bits
// It's an odd integer.
fld qword ptr MO(mzero)
ret
cfi_adjust_cfa_offset (8)
L22: fstp st(0)
L23: add esp, 8 // Don't use 2 x pop
cfi_adjust_cfa_offset (-8)
L24: fld qword ptr MO(zero)
ret
END
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