1 /* ix87 specific implementation of pow function.
2 Copyright (C) 1996-1997, 1999, 2001, 2004, 2005, 2007, 2011-2012
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, see
19 <http://www.gnu.org/licenses/>. */
21 #include <machine/asm.h>
23 .section .rodata.cst8,"aM",@progbits,8
26 ASM_TYPE_DIRECTIVE(one,@object)
28 ASM_SIZE_DIRECTIVE(one)
29 ASM_TYPE_DIRECTIVE(limit,@object)
31 ASM_SIZE_DIRECTIVE(limit)
32 ASM_TYPE_DIRECTIVE(p31,@object)
33 p31: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x41
34 ASM_SIZE_DIRECTIVE(p31)
36 .section .rodata.cst16,"aM",@progbits,16
39 ASM_TYPE_DIRECTIVE(infinity,@object)
42 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
43 ASM_SIZE_DIRECTIVE(infinity)
44 ASM_TYPE_DIRECTIVE(zero,@object)
46 ASM_SIZE_DIRECTIVE(zero)
47 ASM_TYPE_DIRECTIVE(minf_mzero,@object)
50 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
52 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
53 ASM_SIZE_DIRECTIVE(minf_mzero)
56 # define MO(op) op##@GOTOFF(%ecx)
57 # define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
60 # define MOX(op,x,f) op(,x,f)
75 cmpb $0x40, %ah // is y == 0 ?
78 cmpb $0x05, %ah // is y == ±inf ?
81 cmpb $0x01, %ah // is y == NaN ?
87 cfi_adjust_cfa_offset (4)
101 /* fistpl raises invalid exception for |y| >= 1L<<31. */
104 fcompl MO(p31) // y : x
109 /* First see whether `y' is a natural number. In this case we
110 can use a more precise algorithm. */
112 fistpl (%esp) // y : x
113 fildl (%esp) // int(y) : y : x
114 fucomp %st(1) // y : x
119 /* OK, we have an integer value for y. */
121 cfi_adjust_cfa_offset (-4)
124 jns 4f // y >= 0, jump
125 fdivrl MO(one) // 1/x (now referred to as x)
127 4: fldl MO(one) // 1 : x
133 fmul %st(1) // x : ST*x
135 5: fmul %st(0), %st // x*x : ST*x
142 30: flds 4(%esp) // x : y
143 fldl MO(one) // 1.0 : x : y
144 fucomp %st(1) // x : y
152 cfi_adjust_cfa_offset (4)
154 2: /* y is a large integer (so even). */
159 3: /* y is a real number. */
161 fldl MO(one) // 1.0 : x : y
162 fldl MO(limit) // 0.29 : 1.0 : x : y
163 fld %st(2) // x : 0.29 : 1.0 : x : y
164 fsub %st(2) // x-1 : 0.29 : 1.0 : x : y
165 fabs // |x-1| : 0.29 : 1.0 : x : y
166 fucompp // 1.0 : x : y
171 fsub %st(1) // x-1 : 1.0 : y
172 fyl2xp1 // log2(x) : y
175 7: fyl2x // log2(x) : y
176 8: fmul %st(1) // y*log2(x) : y
177 fst %st(1) // y*log2(x) : y*log2(x)
178 frndint // int(y*log2(x)) : y*log2(x)
179 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
180 fxch // fract(y*log2(x)) : int(y*log2(x))
181 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
182 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
183 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
185 cfi_adjust_cfa_offset (-4)
186 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
192 11: fstp %st(0) // pop y
198 12: fstp %st(0) // pop y
200 flds 4(%esp) // x : 1
202 fucompp // < 1, == 1, or > 1
206 je 13f // jump if x is NaN
209 je 14f // jump if |x| == 1
214 fldl MOX(inf_zero, %edx, 4)
222 13: flds 4(%esp) // load x == NaN
225 cfi_adjust_cfa_offset (4)
230 jz 16f // jump if x == +inf
232 // fistpl raises invalid exception for |y| >= 1L<<31, so test
233 // that (in which case y is certainly even) before testing
242 // We must find out whether y is an odd integer.
245 fildl (%esp) // int(y) : y
251 // OK, the value is an integer.
253 cfi_adjust_cfa_offset (-4)
255 jz 18f // jump if not odd
256 // It's an odd integer.
258 fldl MOX(minf_mzero, %edx, 8)
261 cfi_adjust_cfa_offset (4)
265 cfi_adjust_cfa_offset (-4)
269 fldl MOX(inf_zero, %eax, 1)
272 cfi_adjust_cfa_offset (4)
274 17: shll $30, %edx // sign bit for y in right position
276 cfi_adjust_cfa_offset (-4)
278 fldl MOX(inf_zero, %edx, 8)
281 cfi_adjust_cfa_offset (4)
288 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
292 // fistpl raises invalid exception for |y| >= 1L<<31, so test
293 // that (in which case y is certainly even) before testing
304 fildl (%esp) // int(y) : y
310 // OK, the value is an integer.
312 cfi_adjust_cfa_offset (-4)
314 jz 27f // jump if not odd
315 // It's an odd integer.
316 // Raise divide-by-zero exception and get minus infinity value.
322 cfi_adjust_cfa_offset (4)
325 cfi_adjust_cfa_offset (-4)
326 27: // Raise divide-by-zero exception and get infinity value.
331 cfi_adjust_cfa_offset (4)
333 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
337 // fistpl raises invalid exception for |y| >= 1L<<31, so test
338 // that (in which case y is certainly even) before testing
347 fildl (%esp) // int(y) : y
353 // OK, the value is an integer.
355 cfi_adjust_cfa_offset (-4)
357 jz 24f // jump if not odd
358 // It's an odd integer.
362 cfi_adjust_cfa_offset (4)
364 23: addl $4, %esp // Don't use pop.
365 cfi_adjust_cfa_offset (-4)
370 strong_alias (__ieee754_powf, __powf_finite)