1 /* ix87 specific implementation of pow function.
2 Copyright (C) 1996, 1997, 1998, 1999, 2001, 2004
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>
31 ASM_TYPE_DIRECTIVE(infinity,@object)
34 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
35 ASM_SIZE_DIRECTIVE(infinity)
36 ASM_TYPE_DIRECTIVE(zero,@object)
38 ASM_SIZE_DIRECTIVE(zero)
39 ASM_TYPE_DIRECTIVE(minf_mzero,@object)
42 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
44 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
45 ASM_SIZE_DIRECTIVE(minf_mzero)
46 ASM_TYPE_DIRECTIVE(one,@object)
48 ASM_SIZE_DIRECTIVE(one)
49 ASM_TYPE_DIRECTIVE(limit,@object)
51 ASM_SIZE_DIRECTIVE(limit)
52 ASM_TYPE_DIRECTIVE(p63,@object)
53 p63: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43
54 ASM_SIZE_DIRECTIVE(p63)
57 #define MO(op) op##@GOTOFF(%ecx)
58 #define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
61 #define MOX(op,x,f) op(,x,f)
72 addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ecx
78 cmpb $0x40, %ah // is y == 0 ?
81 cmpb $0x05, %ah // is y == ±inf ?
84 cmpb $0x01, %ah // is y == NaN ?
103 /* fistpll raises invalid exception for |y| >= 1L<<63. */
106 fcompl MO(p63) // y : x
111 /* First see whether `y' is a natural number. In this case we
112 can use a more precise algorithm. */
114 fistpll (%esp) // y : x
115 fildll (%esp) // int(y) : y : x
116 fucomp %st(1) // y : x
121 /* OK, we have an integer value for y. */
126 jns 4f // y >= 0, jump
127 fdivrl MO(one) // 1/x (now referred to as x)
131 4: fldl MO(one) // 1 : x
134 6: shrdl $1, %edx, %eax
137 fmul %st(1) // x : ST*x
139 5: fmul %st(0), %st // x*x : ST*x
148 30: fldl 4(%esp) // x : y
149 fldl MO(one) // 1.0 : x : y
150 fucomp %st(1) // x : y
159 2: /* y is a real number. */
161 fldl MO(one) // 1.0 : x : y
162 fld %st(1) // x : 1.0 : x : y
163 fsub %st(1) // x-1 : 1.0 : x : y
164 fabs // |x-1| : 1.0 : x : y
165 fcompl MO(limit) // 1.0 : x : y
170 fsub %st(1) // x-1 : 1.0 : y
171 fyl2xp1 // log2(x) : y
174 7: fyl2x // log2(x) : y
175 8: fmul %st(1) // y*log2(x) : y
176 fst %st(1) // y*log2(x) : y*log2(x)
177 frndint // int(y*log2(x)) : y*log2(x)
178 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
179 fxch // fract(y*log2(x)) : int(y*log2(x))
180 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
181 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
182 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
184 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
190 11: fstp %st(0) // pop y
196 12: fstp %st(0) // pop y
199 fcompl MO(one) // < 1, == 1, or > 1
203 je 13f // jump if x is NaN
206 je 14f // jump if |x| == 1
211 fldl MOX(inf_zero, %edx, 4)
219 13: fldl 4(%esp) // load x == NaN
226 jz 16f // jump if x == +inf
228 // We must find out whether y is an odd integer.
231 fildll (%esp) // int(y) : y
237 // OK, the value is an integer, but is the number of bits small
238 // enough so that all are coming from the mantissa?
242 jz 18f // jump if not odd
247 155: cmpl $0x00200000, %eax
248 ja 18f // does not fit in mantissa bits
249 // It's an odd integer.
251 fldl MOX(minf_mzero, %edx, 8)
260 fldl MOX(inf_zero, %eax, 1)
264 17: shll $30, %edx // sign bit for y in right position
267 fldl MOX(inf_zero, %edx, 8)
276 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
282 fildll (%esp) // int(y) : y
288 // OK, the value is an integer, but is the number of bits small
289 // enough so that all are coming from the mantissa?
293 jz 27f // jump if not odd
294 cmpl $0xffe00000, %edx
295 jbe 27f // does not fit in mantissa bits
296 // It's an odd integer.
297 // Raise divide-by-zero exception and get minus infinity value.
305 27: // Raise divide-by-zero exception and get infinity value.
311 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
317 fildll (%esp) // int(y) : y
323 // OK, the value is an integer, but is the number of bits small
324 // enough so that all are coming from the mantissa?
328 jz 24f // jump if not odd
329 cmpl $0xffe00000, %edx
330 jae 24f // does not fit in mantissa bits
331 // It's an odd integer.
336 23: addl $8, %esp // Don't use 2 x pop