1 /* ix87 specific implementation of pow function.
2 Copyright (C) 1996-2013 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, see
18 <http://www.gnu.org/licenses/>. */
20 #include <machine/asm.h>
22 .section .rodata.cst8,"aM",@progbits,8
27 ASM_SIZE_DIRECTIVE(one)
30 ASM_SIZE_DIRECTIVE(limit)
32 p31: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x41
33 ASM_SIZE_DIRECTIVE(p31)
35 .section .rodata.cst16,"aM",@progbits,16
38 .type infinity,@object
41 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
42 ASM_SIZE_DIRECTIVE(infinity)
45 ASM_SIZE_DIRECTIVE(zero)
46 .type minf_mzero,@object
49 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
51 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
52 ASM_SIZE_DIRECTIVE(minf_mzero)
55 # define MO(op) op##@GOTOFF(%ecx)
56 # define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
59 # define MOX(op,x,f) op(,x,f)
74 cmpb $0x40, %ah // is y == 0 ?
77 cmpb $0x05, %ah // is y == ±inf ?
80 cmpb $0x01, %ah // is y == NaN ?
86 cfi_adjust_cfa_offset (4)
103 /* fistpl raises invalid exception for |y| >= 1L<<31. */
106 fcompl MO(p31) // y : x
111 /* First see whether `y' is a natural number. In this case we
112 can use a more precise algorithm. */
114 fistpl (%esp) // y : x
115 fildl (%esp) // int(y) : y : x
116 fucomp %st(1) // y : x
121 /* OK, we have an integer value for y. */
123 cfi_adjust_cfa_offset (-4)
126 jns 4f // y >= 0, jump
127 fdivrl MO(one) // 1/x (now referred to as x)
129 4: fldl MO(one) // 1 : x
135 fmul %st(1) // x : ST*x
137 5: fmul %st(0), %st // x*x : ST*x
144 30: flds 4(%esp) // x : y
145 fldl MO(one) // 1.0 : x : y
146 fucomp %st(1) // x : y
154 cfi_adjust_cfa_offset (4)
156 2: /* y is a large integer (so even). */
161 3: /* y is a real number. */
163 fldl MO(one) // 1.0 : x : y
164 fldl MO(limit) // 0.29 : 1.0 : x : y
165 fld %st(2) // x : 0.29 : 1.0 : x : y
166 fsub %st(2) // x-1 : 0.29 : 1.0 : x : y
167 fabs // |x-1| : 0.29 : 1.0 : x : y
168 fucompp // 1.0 : x : y
173 fsub %st(1) // x-1 : 1.0 : y
174 fyl2xp1 // log2(x) : y
177 7: fyl2x // log2(x) : y
178 8: fmul %st(1) // y*log2(x) : y
179 fst %st(1) // y*log2(x) : y*log2(x)
180 frndint // int(y*log2(x)) : y*log2(x)
181 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
182 fxch // fract(y*log2(x)) : int(y*log2(x))
183 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
184 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
185 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
187 cfi_adjust_cfa_offset (-4)
188 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
194 11: fstp %st(0) // pop y
200 12: fstp %st(0) // pop y
202 flds 4(%esp) // x : 1
204 fucompp // < 1, == 1, or > 1
208 je 13f // jump if x is NaN
211 je 14f // jump if |x| == 1
216 fldl MOX(inf_zero, %edx, 4)
224 13: flds 4(%esp) // load x == NaN
227 cfi_adjust_cfa_offset (4)
232 jz 16f // jump if x == +inf
234 // fistpl raises invalid exception for |y| >= 1L<<31, so test
235 // that (in which case y is certainly even) before testing
244 // We must find out whether y is an odd integer.
247 fildl (%esp) // int(y) : y
253 // OK, the value is an integer.
255 cfi_adjust_cfa_offset (-4)
257 jz 18f // jump if not odd
258 // It's an odd integer.
260 fldl MOX(minf_mzero, %edx, 8)
263 cfi_adjust_cfa_offset (4)
267 cfi_adjust_cfa_offset (-4)
271 fldl MOX(inf_zero, %eax, 1)
274 cfi_adjust_cfa_offset (4)
276 17: shll $30, %edx // sign bit for y in right position
278 cfi_adjust_cfa_offset (-4)
280 fldl MOX(inf_zero, %edx, 8)
283 cfi_adjust_cfa_offset (4)
290 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
294 // fistpl raises invalid exception for |y| >= 1L<<31, so test
295 // that (in which case y is certainly even) before testing
306 fildl (%esp) // int(y) : y
312 // OK, the value is an integer.
314 cfi_adjust_cfa_offset (-4)
316 jz 27f // jump if not odd
317 // It's an odd integer.
318 // Raise divide-by-zero exception and get minus infinity value.
324 cfi_adjust_cfa_offset (4)
327 cfi_adjust_cfa_offset (-4)
328 27: // Raise divide-by-zero exception and get infinity value.
333 cfi_adjust_cfa_offset (4)
335 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
339 // fistpl raises invalid exception for |y| >= 1L<<31, so test
340 // that (in which case y is certainly even) before testing
349 fildl (%esp) // int(y) : y
355 // OK, the value is an integer.
357 cfi_adjust_cfa_offset (-4)
359 jz 24f // jump if not odd
360 // It's an odd integer.
364 cfi_adjust_cfa_offset (4)
366 23: addl $4, %esp // Don't use pop.
367 cfi_adjust_cfa_offset (-4)
372 strong_alias (__ieee754_powf, __powf_finite)