Mercurial > sdl-ios-xcode
view src/hermes/HeadMMX.h @ 3880:74e828c64315 SDL-1.2
Fixed bug #292
I might be on crack here.
It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and
right channels of a stereo stream together, and clamps the new mono channel if
it would overflow.
Shouldn't it be dividing by 2 to average the two sample points instead of
clamping? Otherwise the mono sample point's volume doubles in the conversion.
This would also make the conversion faster, as it replaces two branches per
sample frame with a bitwise shift.
--ryan.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 24 Sep 2006 15:45:37 +0000 |
parents | d910939febfa |
children | 782fd950bd46 c121d94672cb 39b9405d3cb6 |
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/* Header definitions for the MMX routines for the HERMES library Copyright (c) 1998 Christian Nentwich (c.nentwich@cs.ucl.ac.uk) This source code is licensed under the GNU LGPL Please refer to the file COPYING.LIB contained in the distribution for licensing conditions */ #include "SDL_config.h" #ifndef __HERMES_HEAD_MMX__ #define __HERMES_HEAD_MMX__ /* If you cannot stand ifdefs, then please do not look into this file, it's going to end your life :) */ #ifdef X86_ASSEMBLER #ifdef __cplusplus extern "C" { #endif void STACKCALL ConvertMMX(HermesConverterInterface *); void STACKCALL ClearMMX_32(HermesClearInterface *); void STACKCALL ClearMMX_24(HermesClearInterface *); void STACKCALL ClearMMX_16(HermesClearInterface *); void STACKCALL ClearMMX_8(HermesClearInterface *); void ConvertMMXpII32_24RGB888(); void ConvertMMXpII32_16RGB565(); void ConvertMMXpII32_16BGR565(); void ConvertMMXpII32_16RGB555(); void ConvertMMXpII32_16BGR565(); void ConvertMMXpII32_16BGR555(); void ConvertMMXp32_16RGB555(); #ifdef __cplusplus } #endif /* Fix the underscore business with ELF compilers */ #if defined(__ELF__) && defined(__GNUC__) #ifdef __cplusplus extern "C" { #endif extern void _ConvertMMX(HermesConverterInterface *); extern void _ConvertMMXpII32_24RGB888(); extern void _ConvertMMXpII32_16RGB565(); extern void _ConvertMMXpII32_16BGR565(); extern void _ConvertMMXpII32_16RGB555(); extern void _ConvertMMXpII32_16BGR555(); #define ConvertMMX _ConvertMMX #define ConvertMMXpII32_24RGB888 _ConvertMMXpII32_24RGB888 #define ConvertMMXpII32_16RGB565 _ConvertMMXpII32_16RGB565 #define ConvertMMXpII32_16BGR565 _ConvertMMXpII32_16BGR565 #define ConvertMMXpII32_16RGB555 _ConvertMMXpII32_16RGB555 #define ConvertMMXpII32_16BGR555 _ConvertMMXpII32_16BGR555 #ifdef __cplusplus } #endif #endif /* ELF and GNUC */ /* Make it work with Watcom */ #ifdef __WATCOMC__ #pragma warning 601 9 #pragma aux ConvertMMX "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearMMX_32 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearMMX_24 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearMMX_16 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearMMX_8 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ConvertMMXpII32_24RGB888 "_*" #pragma aux ConvertMMXpII32_16RGB565 "_*" #pragma aux ConvertMMXpII32_16BGR565 "_*" #pragma aux ConvertMMXpII32_16RGB555 "_*" #pragma aux ConvertMMXpII32_16BGR555 "_*" #pragma aux ConvertMMXp32_16RGB555 "_*" #endif /* WATCOM */ #endif /* X86_ASSEMBLER */ #endif