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71 lines
2.4 KiB
ArmAsm
71 lines
2.4 KiB
ArmAsm
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/* ix87 specific implementation of exp(x)-1.
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Copyright (C) 1996, 1997, 2005 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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Based on code by John C. Bowman <bowman@ipp-garching.mpg.de>.
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Corrections by H.J. Lu (hjl@gnu.ai.mit.edu), 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/* Using: e^x - 1 = 2^(x * log2(e)) - 1 */
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.file "s_expm1.s"
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.text
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.align 4
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minus1: .double -1.0
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one: .double 1.0
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l2e: .tfloat 1.442695040888963407359924681002
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.align 4
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.globl ___expm1
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.def __expm1; .scl 2; .type 32; .endef
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___expm1:
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fldl 4(%esp) # x
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fxam # Is NaN or +-Inf?
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fstsw %ax
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movb $0x45, %ch
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andb %ah, %ch
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cmpb $0x40, %ch
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je 3f # If +-0, jump.
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cmpb $0x05, %ch
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je 2f # If +-Inf, jump.
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fldt l2e # log2(e) : x
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fmulp # log2(e)*x
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fld %st # log2(e)*x : log2(e)*x
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frndint # int(log2(e)*x) : log2(e)*x
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fsubr %st, %st(1) # int(log2(e)*x) : fract(log2(e)*x)
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fxch # fract(log2(e)*x) : int(log2(e)*x)
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f2xm1 # 2^fract(log2(e)*x)-1 : int(log2(e)*x)
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fscale # 2^(log2(e)*x)-2^int(log2(e)*x) : int(log2(e)*x)
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fxch # int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fldl one # 1 : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fscale # 2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fsubrl one # 1-2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fstp %st(1) # 1-2^int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
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fsubrp %st, %st(1) # 2^(log2(e)*x)
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ret
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2: testl $0x200, %eax # Test sign.
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jz 3f # If positive, jump.
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fstp %st
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fldl minus1 # Set result to -1.0.
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3: ret
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