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@@ -119,25 +119,57 @@
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{$define FPC_SYSTEM_HAS_EXP}
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function fpc_exp_real(d : ValReal) : ValReal;assembler;compilerproc;
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- var
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- cw1,cw2: word;
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asm
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- // comes from DJ GPP
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fldt d
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fldl2e
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- fmulp %st,%st(1)
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- fstcw CW1
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- fstcw CW2
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- fwait
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- andw $0xf3ff,CW2
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- orw $0x0400,CW2
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- fldcw CW2
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- fld %st(0)
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+ fmul %st(1),%st { z = d * log2(e) }
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frndint
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- fldcw CW1
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- fxch %st(1)
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- fsub %st(1),%st
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+ { Calculate frac(z) using modular arithmetic to avoid precision loss.
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+ Avoid PIC hacks by using immediate operands (it's not the fastest,
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+ but likely the cleanest solution). }
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+ pushl $0x3fe62e42 { ln(2).hi=6.9314718036912382E-001 }
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+ pushl $0xfee00000
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+ fldl (%esp)
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+ fmul %st(1),%st
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+ fsubrp %st,%st(2)
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+ pushl $0x3dea39ef { ln(2).lo=1.9082149292705877E-010 }
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+ pushl $0x35793c76
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+ fldl (%esp)
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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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+
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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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+ jae .L1 { frac(z) <= 1 }
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+ fld %st(1)
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+ fabs
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+ pushl $0x46c00000 { single(24576.0) }
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+ fcomps (%esp)
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+ fstsw %ax
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+ sahf
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+ jb .L0 { int(z) < 24576 }
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+ fsub %st,%st
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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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+ pushl $0x3f000000 { single(0.5) }
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+ fmuls (%esp)
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+ f2xm1
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+ fld %st
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+ pushl $0x40000000 { single(2.0) }
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+ fadds (%esp)
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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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faddp %st,%st(1)
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fscale
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sergei