1 /* ix87 specific implementation of pow function.
2 Copyright (C) 1996, 1997, 1998, 1999, 2001, 2004, 2005, 2007, 2011
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, write to the Free
19 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 #include <machine/asm.h>
25 .section .rodata.cst8,"aM",@progbits,8
30 ASM_TYPE_DIRECTIVE(one,@object)
32 ASM_SIZE_DIRECTIVE(one)
33 ASM_TYPE_DIRECTIVE(limit,@object)
35 ASM_SIZE_DIRECTIVE(limit)
36 ASM_TYPE_DIRECTIVE(p63,@object)
37 p63: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43
38 ASM_SIZE_DIRECTIVE(p63)
41 .section .rodata.cst16,"aM",@progbits,16
46 ASM_TYPE_DIRECTIVE(infinity,@object)
49 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
50 ASM_SIZE_DIRECTIVE(infinity)
51 ASM_TYPE_DIRECTIVE(zero,@object)
53 ASM_SIZE_DIRECTIVE(zero)
54 ASM_TYPE_DIRECTIVE(minf_mzero,@object)
57 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
59 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
60 ASM_SIZE_DIRECTIVE(minf_mzero)
63 # define MO(op) op##@GOTOFF(%ecx)
64 # define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
67 # define MOX(op,x,f) op(,x,f)
82 cmpb $0x40, %ah // is y == 0 ?
85 cmpb $0x05, %ah // is y == ±inf ?
88 cmpb $0x01, %ah // is y == NaN ?
94 cfi_adjust_cfa_offset (8)
108 /* fistpll raises invalid exception for |y| >= 1L<<63. */
111 fcompl MO(p63) // y : x
116 /* First see whether `y' is a natural number. In this case we
117 can use a more precise algorithm. */
119 fistpll (%esp) // y : x
120 fildll (%esp) // int(y) : y : x
121 fucomp %st(1) // y : x
126 /* OK, we have an integer value for y. */
128 cfi_adjust_cfa_offset (-4)
130 cfi_adjust_cfa_offset (-4)
133 jns 4f // y >= 0, jump
134 fdivrl MO(one) // 1/x (now referred to as x)
138 4: fldl MO(one) // 1 : x
141 6: shrdl $1, %edx, %eax
144 fmul %st(1) // x : ST*x
146 5: fmul %st(0), %st // x*x : ST*x
155 30: fldt 4(%esp) // x : y
156 fldl MO(one) // 1.0 : x : y
157 fucomp %st(1) // x : y
165 cfi_adjust_cfa_offset (8)
167 2: /* y is a real number. */
169 fldl MO(one) // 1.0 : x : y
170 fldl MO(limit) // 0.29 : 1.0 : x : y
171 fld %st(2) // x : 0.29 : 1.0 : x : y
172 fsub %st(2) // x-1 : 0.29 : 1.0 : x : y
173 fabs // |x-1| : 0.29 : 1.0 : x : y
174 fucompp // 1.0 : x : y
179 fsub %st(1) // x-1 : 1.0 : y
180 fyl2xp1 // log2(x) : y
183 7: fyl2x // log2(x) : y
184 8: fmul %st(1) // y*log2(x) : y
188 cmpb $0x05, %ah // is y*log2(x) == ±inf ?
190 fst %st(1) // y*log2(x) : y*log2(x)
191 frndint // int(y*log2(x)) : y*log2(x)
192 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
193 fxch // fract(y*log2(x)) : int(y*log2(x))
194 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
195 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
196 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
198 cfi_adjust_cfa_offset (-8)
199 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
202 cfi_adjust_cfa_offset (8)
203 28: fstp %st(1) // y*log2(x)
204 fldl MO(one) // 1 : y*log2(x)
205 fscale // 2^(y*log2(x)) : y*log2(x)
207 cfi_adjust_cfa_offset (-8)
208 fstp %st(1) // 2^(y*log2(x))
213 11: fstp %st(0) // pop y
219 12: fstp %st(0) // pop y
221 fldt 4(%esp) // x : 1
223 fucompp // < 1, == 1, or > 1
227 je 13f // jump if x is NaN
230 je 14f // jump if |x| == 1
235 fldl MOX(inf_zero, %edx, 4)
243 13: fldt 4(%esp) // load x == NaN
246 cfi_adjust_cfa_offset (8)
251 jz 16f // jump if x == +inf
253 // We must find out whether y is an odd integer.
256 fildll (%esp) // int(y) : y
262 // OK, the value is an integer, but is it odd?
264 cfi_adjust_cfa_offset (-4)
266 cfi_adjust_cfa_offset (-4)
268 jz 18f // jump if not odd
269 // It's an odd integer.
271 fldl MOX(minf_mzero, %edx, 8)
274 cfi_adjust_cfa_offset (8)
278 cfi_adjust_cfa_offset (-8)
282 fldl MOX(inf_zero, %eax, 1)
285 cfi_adjust_cfa_offset (8)
287 17: shll $30, %edx // sign bit for y in right position
289 cfi_adjust_cfa_offset (-8)
291 fldl MOX(inf_zero, %edx, 8)
294 cfi_adjust_cfa_offset (8)
301 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
307 fildll (%esp) // int(y) : y
313 // OK, the value is an integer, but is it odd?
315 cfi_adjust_cfa_offset (-4)
317 cfi_adjust_cfa_offset (-4)
319 jz 27f // jump if not odd
320 // It's an odd integer.
321 // Raise divide-by-zero exception and get minus infinity value.
327 cfi_adjust_cfa_offset (8)
330 cfi_adjust_cfa_offset (-8)
331 27: // Raise divide-by-zero exception and get infinity value.
336 cfi_adjust_cfa_offset (8)
338 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
344 fildll (%esp) // int(y) : y
350 // OK, the value is an integer, but is it odd?
352 cfi_adjust_cfa_offset (-4)
354 cfi_adjust_cfa_offset (-4)
356 jz 24f // jump if not odd
357 // It's an odd integer.
361 cfi_adjust_cfa_offset (8)
363 23: addl $8, %esp // Don't use 2 x pop
364 cfi_adjust_cfa_offset (-8)
369 strong_alias (__ieee754_powl, __powl_finite)