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 p63: .byte 0, 0, 0, 0, 0, 0, 0xe0, 0x43
33 ASM_SIZE_DIRECTIVE(p63)
35 p10: .byte 0, 0, 0, 0, 0, 0, 0x90, 0x40
36 ASM_SIZE_DIRECTIVE(p10)
38 .section .rodata.cst16,"aM",@progbits,16
41 .type infinity,@object
44 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0x7f
45 ASM_SIZE_DIRECTIVE(infinity)
48 ASM_SIZE_DIRECTIVE(zero)
49 .type minf_mzero,@object
52 .byte 0, 0, 0, 0, 0, 0, 0xf0, 0xff
54 .byte 0, 0, 0, 0, 0, 0, 0, 0x80
55 ASM_SIZE_DIRECTIVE(minf_mzero)
58 # define MO(op) op##@GOTOFF(%ecx)
59 # define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
62 # define MOX(op,x,f) op(,x,f)
77 cmpb $0x40, %ah // is y == 0 ?
80 cmpb $0x05, %ah // is y == ±inf ?
83 cmpb $0x01, %ah // is y == NaN ?
89 cfi_adjust_cfa_offset (8)
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. If large enough that
122 errors may propagate out of the 11 bits excess precision, use
123 the algorithm for real exponent instead. */
126 fcompl MO(p10) // y : x
131 cfi_adjust_cfa_offset (-4)
133 cfi_adjust_cfa_offset (-4)
136 jns 4f // y >= 0, jump
137 fdivrl MO(one) // 1/x (now referred to as x)
141 4: fldl MO(one) // 1 : x
144 6: shrdl $1, %edx, %eax
147 fmul %st(1) // x : ST*x
149 5: fmul %st(0), %st // x*x : ST*x
158 30: fldl 4(%esp) // x : y
159 fldl MO(one) // 1.0 : x : y
160 fucomp %st(1) // x : y
168 cfi_adjust_cfa_offset (8)
170 2: // y is a large integer (absolute value at least 1L<<10), but
171 // may be odd unless at least 1L<<64. So it may be necessary
172 // to adjust the sign of a negative result afterwards.
177 3: /* y is a real number. */
179 fldl MO(one) // 1.0 : x : y
180 fldl MO(limit) // 0.29 : 1.0 : x : y
181 fld %st(2) // x : 0.29 : 1.0 : x : y
182 fsub %st(2) // x-1 : 0.29 : 1.0 : x : y
183 fabs // |x-1| : 0.29 : 1.0 : x : y
184 fucompp // 1.0 : x : y
189 fsub %st(1) // x-1 : 1.0 : y
190 fyl2xp1 // log2(x) : y
193 7: fyl2x // log2(x) : y
194 8: fmul %st(1) // y*log2(x) : y
195 fst %st(1) // y*log2(x) : y*log2(x)
196 frndint // int(y*log2(x)) : y*log2(x)
197 fsubr %st, %st(1) // int(y*log2(x)) : fract(y*log2(x))
198 fxch // fract(y*log2(x)) : int(y*log2(x))
199 f2xm1 // 2^fract(y*log2(x))-1 : int(y*log2(x))
200 faddl MO(one) // 2^fract(y*log2(x)) : int(y*log2(x))
201 fscale // 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
202 fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
205 // x is negative. If y is an odd integer, negate the result.
206 fldl 20(%esp) // y : abs(result)
207 fld %st // y : y : abs(result)
208 fabs // |y| : y : abs(result)
209 fcompl MO(p63) // y : abs(result)
214 // We must find out whether y is an odd integer.
215 fld %st // y : y : abs(result)
216 fistpll (%esp) // y : abs(result)
217 fildll (%esp) // int(y) : y : abs(result)
218 fucompp // abs(result)
223 // OK, the value is an integer, but is it odd?
225 cfi_adjust_cfa_offset (-4)
227 cfi_adjust_cfa_offset (-4)
229 jz 290f // jump if not odd
230 // It's an odd integer.
233 cfi_adjust_cfa_offset (8)
234 291: fstp %st(0) // abs(result)
236 cfi_adjust_cfa_offset (-8)
242 11: fstp %st(0) // pop y
248 12: fstp %st(0) // pop y
250 fldl 4(%esp) // x : 1
252 fucompp // < 1, == 1, or > 1
256 je 13f // jump if x is NaN
259 je 14f // jump if |x| == 1
264 fldl MOX(inf_zero, %edx, 4)
272 13: fldl 4(%esp) // load x == NaN
275 cfi_adjust_cfa_offset (8)
280 jz 16f // jump if x == +inf
282 // fistpll raises invalid exception for |y| >= 1L<<63, so test
283 // that (in which case y is certainly even) before testing
292 // We must find out whether y is an odd integer.
295 fildll (%esp) // int(y) : y
301 // OK, the value is an integer.
303 cfi_adjust_cfa_offset (-4)
305 cfi_adjust_cfa_offset (-4)
307 jz 18f // jump if not odd
308 // It's an odd integer.
310 fldl MOX(minf_mzero, %edx, 8)
313 cfi_adjust_cfa_offset (8)
317 cfi_adjust_cfa_offset (-8)
321 fldl MOX(inf_zero, %eax, 1)
324 cfi_adjust_cfa_offset (8)
326 17: shll $30, %edx // sign bit for y in right position
328 cfi_adjust_cfa_offset (-8)
330 fldl MOX(inf_zero, %edx, 8)
333 cfi_adjust_cfa_offset (8)
340 // x is ±0 and y is < 0. We must find out whether y is an odd integer.
344 // fistpll raises invalid exception for |y| >= 1L<<63, so test
345 // that (in which case y is certainly even) before testing
356 fildll (%esp) // int(y) : y
362 // OK, the value is an integer.
364 cfi_adjust_cfa_offset (-4)
366 cfi_adjust_cfa_offset (-4)
368 jz 27f // jump if not odd
369 // It's an odd integer.
370 // Raise divide-by-zero exception and get minus infinity value.
376 cfi_adjust_cfa_offset (8)
379 cfi_adjust_cfa_offset (-8)
380 27: // Raise divide-by-zero exception and get infinity value.
385 cfi_adjust_cfa_offset (8)
387 // x is ±0 and y is > 0. We must find out whether y is an odd integer.
391 // fistpll raises invalid exception for |y| >= 1L<<63, so test
392 // that (in which case y is certainly even) before testing
401 fildll (%esp) // int(y) : y
407 // OK, the value is an integer.
409 cfi_adjust_cfa_offset (-4)
411 cfi_adjust_cfa_offset (-4)
413 jz 24f // jump if not odd
414 // It's an odd integer.
418 cfi_adjust_cfa_offset (8)
420 23: addl $8, %esp // Don't use 2 x pop
421 cfi_adjust_cfa_offset (-8)
426 strong_alias (__ieee754_pow, __pow_finite)