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* Re-implement ln(x) also for x87-based x86_64 targets (counterpart of r27367,r27518,r27552,r27553 for i386 target).
git-svn-id: trunk@29131 -
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@ -12,7 +12,30 @@
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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**********************************************************************}
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**********************************************************************}
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{-------------------------------------------------------------------------
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Using functions from AMath/DAMath libraries, which are covered by the
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following license:
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(C) Copyright 2009-2013 Wolfgang Ehrhardt
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from
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the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software in
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a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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----------------------------------------------------------------------------}
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{$push}
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{$push}
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{$codealign constmin=16}
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{$codealign constmin=16}
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@ -147,25 +170,66 @@ const
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{$ifndef FPC_SYSTEM_HAS_EXP}
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{$ifndef FPC_SYSTEM_HAS_EXP}
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{$define FPC_SYSTEM_HAS_EXP}
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{$define FPC_SYSTEM_HAS_EXP}
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{ exp function adapted from AMath library (C) Copyright 2009-2013 Wolfgang Ehrhardt
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* translated into AT&T syntax
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+ PIC support
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* return +Inf/0 for +Inf/-Inf input, instead of NaN }
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function fpc_exp_real(d : ValReal) : ValReal;assembler;compilerproc;
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function fpc_exp_real(d : ValReal) : ValReal;assembler;compilerproc;
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var
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const
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oldcw,newcw: word;
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ln2hi: double=6.9314718036912382E-001;
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asm
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ln2lo: double=1.9082149292705877E-010;
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// comes from DJ GPP
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large: single=24576.0;
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two: single=2.0;
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half: single=0.5;
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asm
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fldt d
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fldt d
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fldl2e
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fldl2e
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fmulp %st,%st(1)
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fmul %st(1),%st { z = d * log2(e) }
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fstcw oldcw
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fstcw newcw
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andw $0xf3ff,newcw
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orw $0x0400,newcw
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fldcw newcw
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fld %st(0)
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frndint
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frndint
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fldcw oldcw
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{ Calculate frac(z) using modular arithmetic to avoid precision loss }
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fxch %st(1)
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fldl ln2hi(%rip)
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fsub %st(1),%st
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fmul %st(1),%st
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fsubrp %st,%st(2)
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fldl ln2lo(%rip)
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fmul %st(1),%st
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fsubrp %st,%st(2)
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fxch %st(1) { (d-int(z)*ln2_hi)-int(z)*ln2_lo }
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fldl2e
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fmulp %st,%st(1) { frac(z) }
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{ Above calculation can yield |frac(z)|>1, particularly when rounding mode
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is not "round to nearest". f2xm1 is undefined in that case, so it's
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necessary to check }
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fld %st
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fabs
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fld1
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fcompp
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fstsw %ax
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sahf
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jp .L3 { NaN }
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jae .L1 { |frac(z)| <= 1, good }
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fld %st(1)
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fabs
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fcomps large(%rip)
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fstsw %ax
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sahf
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jb .L0 { int(z) < 24576 }
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.L3:
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fstp %st { pop frac(z) and load 0 }
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fldz
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jmp .L1
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.L0:
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{ Calculate 2**frac(z)-1 as N*(N+2), where N=2**(frac(z)/2)-1 }
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fmuls half(%rip)
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f2xm1
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f2xm1
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fld %st
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fadds two(%rip)
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fmulp %st,%st(1)
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jmp .L2
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.L1:
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f2xm1
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.L2:
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fld1
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fld1
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faddp %st,%st(1)
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faddp %st,%st(1)
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fscale
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fscale
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