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target/m68k: implement flog10

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Using a local m68k floatx80_log10()
[copied from previous:
Written by Andreas Grabher for Previous, NeXT Computer Emulator.]

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180305203910.10391-5-laurent@vivier.eu>
This commit is contained in:
Laurent Vivier 2018-03-05 21:39:06 +01:00
parent 50067bd16f
commit 248efb66fb
5 changed files with 67 additions and 0 deletions
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57
target/m68k/softfloat.c
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@ -658,3 +658,60 @@ floatx80 floatx80_logn(floatx80 a, float_status *status)
return a;
}
}
/*----------------------------------------------------------------------------
| Log base 10
*----------------------------------------------------------------------------*/
floatx80 floatx80_log10(floatx80 a, float_status *status)
{
flag aSign;
int32_t aExp;
uint64_t aSig;
int8_t user_rnd_mode, user_rnd_prec;
floatx80 fp0, fp1;
aSig = extractFloatx80Frac(a);
aExp = extractFloatx80Exp(a);
aSign = extractFloatx80Sign(a);
if (aExp == 0x7FFF) {
if ((uint64_t) (aSig << 1)) {
propagateFloatx80NaNOneArg(a, status);
}
if (aSign == 0) {
return packFloatx80(0, floatx80_infinity.high,
floatx80_infinity.low);
}
}
if (aExp == 0 && aSig == 0) {
float_raise(float_flag_divbyzero, status);
return packFloatx80(1, floatx80_infinity.high,
floatx80_infinity.low);
}
if (aSign) {
float_raise(float_flag_invalid, status);
return floatx80_default_nan(status);
}
user_rnd_mode = status->float_rounding_mode;
user_rnd_prec = status->floatx80_rounding_precision;
status->float_rounding_mode = float_round_nearest_even;
status->floatx80_rounding_precision = 80;
fp0 = floatx80_logn(a, status);
fp1 = packFloatx80(0, 0x3FFD, LIT64(0xDE5BD8A937287195)); /* INV_L10 */
status->float_rounding_mode = user_rnd_mode;
status->floatx80_rounding_precision = user_rnd_prec;
a = floatx80_mul(fp0, fp1, status); /* LOGN(X)*INV_L10 */
float_raise(float_flag_inexact, status);
return a;
}