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* Reverted overflow/underflow handling in fpc_exp_real to original state of C port. In particular, changed constant values to typed constants. Resolves #24839.

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* Values like "huge" or "twom1000" must be declared as typed constants, so expressions using them are evaluated at runtime. E.g. "huge*huge" will either raise an overflow exception or will be evaluated as infinity, if overflows are masked. Calling float_raise() is not necessary anymore.
* Also replaced round() by trunc() when converting double to integer, this is how C defines such conversions.

git-svn-id: trunk@25945 -
This commit is contained in:
sergei 2013-11-06 05:02:02 +00:00
parent 3b87e2c386
commit 797653dd14
1 changed files with 17 additions and 19 deletions
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36
rtl/inc/genmath.inc
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@ -737,22 +737,22 @@ invalid:
} }
function fpc_exp_real(d: ValReal):ValReal;compilerproc; function fpc_exp_real(d: ValReal):ValReal;compilerproc;
const const
one = 1.0; one: double = 1.0;
halF : array[0..1] of double = (0.5,-0.5); halF : array[0..1] of double = (0.5,-0.5);
huge = 1.0e+300; huge: double = 1.0e+300;
twom1000 = 9.33263618503218878990e-302; { 2**-1000=0x01700000,0} twom1000: double = 9.33263618503218878990e-302; { 2**-1000=0x01700000,0}
o_threshold = 7.09782712893383973096e+02; { 0x40862E42, 0xFEFA39EF } o_threshold: double = 7.09782712893383973096e+02; { 0x40862E42, 0xFEFA39EF }
u_threshold = -7.45133219101941108420e+02; { 0xc0874910, 0xD52D3051 } u_threshold: double = -7.45133219101941108420e+02; { 0xc0874910, 0xD52D3051 }
ln2HI : array[0..1] of double = ( 6.93147180369123816490e-01, { 0x3fe62e42, 0xfee00000 } ln2HI : array[0..1] of double = ( 6.93147180369123816490e-01, { 0x3fe62e42, 0xfee00000 }
-6.93147180369123816490e-01); { 0xbfe62e42, 0xfee00000 } -6.93147180369123816490e-01); { 0xbfe62e42, 0xfee00000 }
ln2LO : array[0..1] of double = (1.90821492927058770002e-10, { 0x3dea39ef, 0x35793c76 } ln2LO : array[0..1] of double = (1.90821492927058770002e-10, { 0x3dea39ef, 0x35793c76 }
-1.90821492927058770002e-10); { 0xbdea39ef, 0x35793c76 } -1.90821492927058770002e-10); { 0xbdea39ef, 0x35793c76 }
invln2 = 1.44269504088896338700e+00; { 0x3ff71547, 0x652b82fe } invln2: double = 1.44269504088896338700e+00; { 0x3ff71547, 0x652b82fe }
P1 = 1.66666666666666019037e-01; { 0x3FC55555, 0x5555553E } P1: double = 1.66666666666666019037e-01; { 0x3FC55555, 0x5555553E }
P2 = -2.77777777770155933842e-03; { 0xBF66C16C, 0x16BEBD93 } P2: double = -2.77777777770155933842e-03; { 0xBF66C16C, 0x16BEBD93 }
P3 = 6.61375632143793436117e-05; { 0x3F11566A, 0xAF25DE2C } P3: double = 6.61375632143793436117e-05; { 0x3F11566A, 0xAF25DE2C }
P4 = -1.65339022054652515390e-06; { 0xBEBBBD41, 0xC5D26BF1 } P4: double = -1.65339022054652515390e-06; { 0xBEBBBD41, 0xC5D26BF1 }
P5 = 4.13813679705723846039e-08; { 0x3E663769, 0x72BEA4D0 } P5: double = 4.13813679705723846039e-08; { 0x3E663769, 0x72BEA4D0 }
var var
c,hi,lo,t,y : double; c,hi,lo,t,y : double;
k,xsb : longint; k,xsb : longint;
@ -786,21 +786,19 @@ invalid:
end end
else else
begin begin
if xsb=0 then begin if xsb=0 then
float_raise(float_flag_overflow);
result:=d result:=d
end else else
result:=0.0; { exp(+-inf)=begininf,0end } result:=0.0; { exp(+-inf)=(inf,0) }
exit; exit;
end; end;
end; end;
if d > o_threshold then begin if d > o_threshold then begin
float_raise(float_flag_overflow); { overflow } result:=huge*huge; { overflow }
exit; exit;
end; end;
if d < u_threshold then begin if d < u_threshold then begin
float_raise(float_flag_underflow); { underflow } result:=twom1000*twom1000; { underflow }
result:=0; { Result if underflow masked }
exit; exit;
end; end;
end; end;
@ -815,7 +813,7 @@ invalid:
end end
else else
begin begin
k := round(invln2*d+halF[xsb]); k := trunc(invln2*d+halF[xsb]);
t := k; t := k;
hi := d - t*ln2HI[0]; { t*ln2HI is exact here } hi := d - t*ln2HI[0]; { t*ln2HI is exact here }
lo := t*ln2LO[0]; lo := t*ln2LO[0];