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[FAST486]

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Due to some kind of mixup, I thought the series for log(x) was actually for log10(x).
Fix Fast486FpuCalculateLogBase2 by dividing the result with log(2) and not log10(2).


svn path=/trunk/; revision=67841
This commit is contained in:
Aleksandar Andrejevic 2015-05-21 17:27:47 +00:00
parent 1e5d331ec6
commit fe362794c6
1 changed files with 5 additions and 5 deletions
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10
reactos/lib/fast486/fpu.c
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@ -1085,8 +1085,8 @@ Fast486FpuCalculateTwoPowerMinusOne(PFAST486_STATE State,
/* /*
* Calculates using the identities: * Calculates using the identities:
* log2(x) = log10(x) / log10(2) * log2(x) = ln(x) / ln(2)
* log10(x)= sum { -1^(n+1) * x^n / n!, n >= 1 } * ln(x)= sum { -1^(n+1) * x^n / n!, n >= 1 }
*/ */
static inline BOOLEAN FASTCALL static inline BOOLEAN FASTCALL
Fast486FpuCalculateLogBase2(PFAST486_STATE State, Fast486FpuCalculateLogBase2(PFAST486_STATE State,
@ -1144,7 +1144,7 @@ Fast486FpuCalculateLogBase2(PFAST486_STATE State,
/* Subtract one from the value */ /* Subtract one from the value */
if (!Fast486FpuSubtract(State, &Value, &FpuOne, &Value)) return FALSE; if (!Fast486FpuSubtract(State, &Value, &FpuOne, &Value)) return FALSE;
/* Calculate the base 10 logarithm */ /* Calculate the natural logarithm */
SeriesElement = TempResult = Value; SeriesElement = TempResult = Value;
for (i = 2; i < INVERSE_NUMBERS_COUNT / 2; i++) for (i = 2; i < INVERSE_NUMBERS_COUNT / 2; i++)
@ -1173,8 +1173,8 @@ Fast486FpuCalculateLogBase2(PFAST486_STATE State,
} }
} }
/* Now convert the base 10 logarithm into a base 2 logarithm */ /* Now convert the natural logarithm into a base 2 logarithm */
if (!Fast486FpuDivide(State, &TempResult, &FpuLgTwo, &TempResult)) return FALSE; if (!Fast486FpuDivide(State, &TempResult, &FpuLnTwo, &TempResult)) return FALSE;
/* /*
* Add the exponent to the result * Add the exponent to the result