Mercurial > sdl-ios-xcode
view src/audio/SDL_mixer_m68k.c @ 2752:edd2839b36f7
http://sources.redhat.com/ml/newlib/2002/msg00230.html
Stephen L Moshier wrote:
>
> pow(x,y) returns 0 when x is very close to -1.0 and y is very large.
> The following test program prints
>
> pow(1.0000000000000002e+00 4.5035996273704970e+15) = 2.7182818284590455e+00
> pow(-1.0000000000000002e+00 4.5035996273704970e+15) =0.0000000000000000e+00
> pow(9.9999999999999978e-01 4.5035996273704970e+15) = 3.6787944117144222e-01
> pow(-9.9999999999999978e-01 4.5035996273704970e+15) = 0.0000000000000000e+00
>
> which is incorrect for the negative arguments raised to an odd integer
> power.
>
> -----
> double pow (double, double);
>
> int
> main ()
> {
> double x, y, z;
>
> x = 1.0 + pow (2.0, -52.0);
> y = 1.0 + pow (2.0, 52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = 1.0 - pow (2.0, -52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> }
> -----
>
> Here is a patch for newlib/libm/math/epow.c:
Patch checked in and duplicated for ef_pow.c. Thanks.
-- Jeff J.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 15 Sep 2008 04:31:30 +0000 |
| parents | c121d94672cb |
| children | 99210400e8b9 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2004 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* m68k assembly mix routines Patrice Mandin */ #if defined(__M68000__) && defined(__GNUC__) void SDL_MixAudio_m68k_U8(char *dst, char *src, long len, long volume, char *mix8) { __asm__ __volatile__("tstl %2\n" " beqs stoploop_u8\n" "mixloop_u8:\n" /* Mix a sample */ " moveq #0,%%d0\n" " moveq #0,%%d1\n" " moveb %1@+,%%d0\n" /* d0 = *src++ */ " sub #128,%%d0\n" /* d0 -= 128 */ " muls %3,%%d0\n" /* d0 *= volume (0<=volume<=128) */ " moveb %0@,%%d1\n" /* d1 = *dst */ " asr #7,%%d0\n" /* d0 /= 128 (SDL_MIX_MAXVOLUME) */ " add #128,%%d0\n" /* d0 += 128 */ " add %%d1,%%d0\n" " moveb %4@(%%d0:w),%0@+\n" /* Loop till done */ " subql #1,%2\n" " bhis mixloop_u8\n" "stoploop_u8:\n": /* no return value */ : /* input */ "a"(dst), "a"(src), "d"(len), "d"(volume), "a"(mix8): /* clobbered registers */ "d0", "d1", "cc", "memory"); } void SDL_MixAudio_m68k_S8(char *dst, char *src, long len, long volume) { __asm__ __volatile__("tstl %2\n" " beqs stoploop_s8\n" " moveq #-128,%%d2\n" " moveq #127,%%d3\n" "mixloop_s8:\n" /* Mix a sample */ " moveq #0,%%d0\n" " moveq #0,%%d1\n" " moveb %1@+,%%d0\n" /* d0 = *src++ */ " muls %3,%%d0\n" /* d0 *= volume (0<=volume<=128) */ " moveb %0@,%%d1\n" /* d1 = *dst */ " asr #7,%%d0\n" /* d0 /= 128 (SDL_MIX_MAXVOLUME) */ " add %%d1,%%d0\n" " cmp %%d2,%%d0\n" " bges lower_limit_s8\n" " move %%d2,%%d0\n" "lower_limit_s8:\n" " cmp %%d3,%%d0\n" " bles upper_limit_s8\n" " move %%d3,%%d0\n" "upper_limit_s8:\n" " moveb %%d0,%0@+\n" /* Loop till done */ " subql #1,%2\n" " bhis mixloop_s8\n" "stoploop_s8:\n": /* no return value */ : /* input */ "a"(dst), "a"(src), "d"(len), "d"(volume): /* clobbered registers */ "d0", "d1", "d2", "d3", "cc", "memory"); } void SDL_MixAudio_m68k_S16MSB(short *dst, short *src, long len, long volume) { __asm__ __volatile__("tstl %2\n" " beqs stoploop_s16msb\n" " movel #-32768,%%d2\n" " movel #32767,%%d3\n" " lsrl #1,%2\n" "mixloop_s16msb:\n" /* Mix a sample */ " move %1@+,%%d0\n" /* d0 = *src++ */ " muls %3,%%d0\n" /* d0 *= volume (0<=volume<=128) */ " move %0@,%%d1\n" /* d1 = *dst */ " extl %%d1\n" /* extend d1 to 32 bits */ " asrl #7,%%d0\n" /* d0 /= 128 (SDL_MIX_MAXVOLUME) */ " addl %%d1,%%d0\n" " cmpl %%d2,%%d0\n" " bges lower_limit_s16msb\n" " move %%d2,%%d0\n" "lower_limit_s16msb:\n" " cmpl %%d3,%%d0\n" " bles upper_limit_s16msb\n" " move %%d3,%%d0\n" "upper_limit_s16msb:\n" " move %%d0,%0@+\n" /* Loop till done */ " subql #1,%2\n" " bhis mixloop_s16msb\n" "stoploop_s16msb:\n": /* no return value */ : /* input */ "a"(dst), "a"(src), "d"(len), "d"(volume): /* clobbered registers */ "d0", "d1", "d2", "d3", "cc", "memory"); } void SDL_MixAudio_m68k_S16LSB(short *dst, short *src, long len, long volume) { __asm__ __volatile__("tstl %2\n" " beqs stoploop_s16lsb\n" " movel #-32768,%%d2\n" " movel #32767,%%d3\n" " lsrl #1,%2\n" "mixloop_s16lsb:\n" /* Mix a sample */ " move %1@+,%%d0\n" /* d0 = *src++ */ " rorw #8,%%d0\n" " muls %3,%%d0\n" /* d0 *= volume (0<=volume<=128) */ " move %0@,%%d1\n" /* d1 = *dst */ " rorw #8,%%d1\n" " extl %%d1\n" /* extend d1 to 32 bits */ " asrl #7,%%d0\n" /* d0 /= 128 (SDL_MIX_MAXVOLUME) */ " addl %%d1,%%d0\n" " cmpl %%d2,%%d0\n" " bges lower_limit_s16lsb\n" " move %%d2,%%d0\n" "lower_limit_s16lsb:\n" " cmpl %%d3,%%d0\n" " bles upper_limit_s16lsb\n" " move %%d3,%%d0\n" "upper_limit_s16lsb:\n" " rorw #8,%%d0\n" " move %%d0,%0@+\n" /* Loop till done */ " subql #1,%2\n" " bhis mixloop_s16lsb\n" "stoploop_s16lsb:\n": /* no return value */ : /* input */ "a"(dst), "a"(src), "d"(len), "d"(volume): /* clobbered registers */ "d0", "d1", "d2", "d3", "cc", "memory"); } #endif /* vi: set ts=4 sw=4 expandtab: */