1 /* ix87 specific implementation of pow function.
2 Copyright (C) 1996, 1997, 1998, 1999, 2001, 2004 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 #include <machine/asm.h>
30 ASM_TYPE_DIRECTIVE(infinity,@object)
33 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
34 ASM_SIZE_DIRECTIVE(infinity)
35 ASM_TYPE_DIRECTIVE(zero,@object)
37 ASM_SIZE_DIRECTIVE(zero)
38 ASM_TYPE_DIRECTIVE(minf_mzero,@object)
41 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
43 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
44 ASM_SIZE_DIRECTIVE(minf_mzero)
45 ASM_TYPE_DIRECTIVE(one,@object)
47 ASM_SIZE_DIRECTIVE(one)
48 ASM_TYPE_DIRECTIVE(limit,@object)
50 ASM_SIZE_DIRECTIVE(limit)
51 ASM_TYPE_DIRECTIVE(p63,@object)
53 .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43
54 ASM_SIZE_DIRECTIVE(p63)
57 #define MO(op) op##(%rip)
71 cmpb $0x40, %ah // is y == 0 ?
74 cmpb $0x05, %ah // is y == ±inf ?
77 cmpb $0x01, %ah // is y == NaN ?
94 /* fistpll raises invalid exception for |y| >= 1L<<63. */
95 fldl MO(p63) // 1L<<63 : y : x
96 fld %st(1) // y : 1L<<63 : y : x
97 fabs // |y| : 1L<<63 : y : x
98 fcomip %st(1), %st // 1L<<63 : y : x
102 /* First see whether `y' is a natural number. In this case we
103 can use a more precise algorithm. */
105 fistpll -8(%rsp) // y : x
106 fildll -8(%rsp) // int(y) : y : x
107 fucomip %st(1),%st // y : x
110 /* OK, we have an integer value for y. */
115 jns 4f // y >= 0, jump
116 fdivrl MO(one) // 1/x (now referred to as x)
120 4: fldl MO(one) // 1 : x
123 6: shrdl $1, %edx, %eax
126 fmul %st(1) // x : ST*x
128 5: fmul %st(0), %st // x*x : ST*x
137 30: fldt 8(%rsp) // x : y
138 fldl MO(one) // 1.0 : x : y
139 fucomip %st(1),%st // x : y
146 2: /* y is a real number. */
148 fldl MO(one) // 1.0 : x : y
149 fld %st(1) // x : 1.0 : x : y
150 fsub %st(1) // x-1 : 1.0 : x : y
151 fabs // |x-1| : 1.0 : x : y
152 fcompl MO(limit) // 1.0 : x : y
157 fsub %st(1) // x-1 : 1.0 : y
158 fyl2xp1 // log2(x) : y
161 7: fyl2x // log2(x) : y
162 8: fmul %st(1) // y*log2(x) : y
166 cmpb $0x05, %ah // is y*log2(x) == ±inf ?
168 fst %st(1) // y*log2(x) : y*log2(x)
169 frndint // int(y*log2(x)) : y*log2(x)
170 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
171 fxch // fract(y*log2(x)) : int(y*log2(x))
172 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
173 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
174 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
175 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
178 28: fstp %st(1) // y*log2(x)
179 fldl MO(one) // 1 : y*log2(x)
180 fscale // 2^(y*log2(x)) : y*log2(x)
181 fstp %st(1) // 2^(y*log2(x))
186 11: fstp %st(0) // pop y
192 12: fstp %st(0) // pop y
195 fcompl MO(one) // < 1, == 1, or > 1
199 je 13f // jump if x is NaN
202 je 14f // jump if |x| == 1
208 lea inf_zero(%rip),%rcx
211 fldl inf_zero(,%rdx, 4)
220 13: fldt 8(%rsp) // load x == NaN
227 jz 16f // jump if x == +inf
229 // We must find out whether y is an odd integer.
231 fistpll -8(%rsp) // y
232 fildll -8(%rsp) // int(y) : y
234 ffreep %st // <empty>
237 // OK, the value is an integer, but is it odd?
241 jz 18f // jump if not odd
242 // It's an odd integer.
245 lea minf_mzero(%rip),%rcx
248 fldl minf_mzero(,%rdx, 8)
258 lea inf_zero(%rip),%rcx
261 fldl inf_zero(,%rax, 1)
266 17: shll $30, %edx // sign bit for y in right position
269 lea inf_zero(%rip),%rcx
272 fldl inf_zero(,%rdx, 8)
282 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
287 fistpll -8(%rsp) // y
288 fildll -8(%rsp) // int(y) : y
290 ffreep %st // <empty>
293 // OK, the value is an integer, but is it odd?
297 jz 27f // jump if not odd
298 // It's an odd integer.
299 // Raise divide-by-zero exception and get minus infinity value.
307 27: // Raise divide-by-zero exception and get infinity value.
313 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
318 fistpll -8(%rsp) // y
319 fildll -8(%rsp) // int(y) : y
321 ffreep %st // <empty>
324 // OK, the value is an integer, but is it odd?
328 jz 24f // jump if not odd
329 // It's an odd integer.