[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 11/11] target-i386: use floatx80_log2() to imple
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 11/11] target-i386: use floatx80_log2() to implement helper_fyl2x*() |
Date: |
Tue, 17 May 2011 08:41:57 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Thunderbird/3.1.10 |
On 05/15/2011 07:13 AM, Aurelien Jarno wrote:
> + temp = floatx80_add(ST0, floatx80_one, &env->fp_status);
> + if (!floatx80_is_neg(temp)) {
> + temp = floatx80_add(ST0, floatx80_one, &env->fp_status);
> + temp = floatx80_log2(temp, &env->fp_status);
> + ST1 = floatx80_mul(ST1, temp, &env->fp_status);
While this is probably better than the existing code, you really
should be using a different series expansion than for log2. This
expansion will be wildly inaccurate for inputs near zero.
r~
- [Qemu-devel] [PATCH 00/11] softfloat-native removal and i386 improvements, Aurelien Jarno, 2011/05/15
- [Qemu-devel] [PATCH 11/11] target-i386: use floatx80_log2() to implement helper_fyl2x*(), Aurelien Jarno, 2011/05/15
- Re: [Qemu-devel] [PATCH 11/11] target-i386: use floatx80_log2() to implement helper_fyl2x*(),
Richard Henderson <=
- [Qemu-devel] [PATCH 01/11] target-ppc: remove old CONFIG_SOFTFLOAT #ifdef, Aurelien Jarno, 2011/05/15
- [Qemu-devel] [PATCH 07/11] softfloat: add float*_is_zero_or_denormal(), Aurelien Jarno, 2011/05/15
- [Qemu-devel] [PATCH 04/11] softfloat: always enable floatx80 and float128 support, Aurelien Jarno, 2011/05/15
- [Qemu-devel] [PATCH 08/11] target-i386: cleanup helper_fxam_ST0(), Aurelien Jarno, 2011/05/15
- [Qemu-devel] [PATCH 06/11] target-i386: use floatx80 constants in helper_fld*_ST0(), Aurelien Jarno, 2011/05/15