view docs/html/sdlmixaudio.html @ 4137:be12463f31ea SDL-1.2

Date: Sat, 2 Feb 2008 22:08:05 +0100 From: Marcus von Appen To: sdl@lists.libsdl.org Subject: [SDL] [Patch] SDL-1.2 SDL_revcpy() asm patch for the cld flag Hi, as reported through the FreeBSD bug tracking system in SDL 1.2.13 (and in the 1.2 branch, if I see that correctly) the SDL_revcpy() macro sets the direction flag (std), but does not clear it afterwards (cld), which is wrong according to the GCC and SYS V specs. This can cause some weird side effects, which in turn can lead to memory corruption. You can read the full report with a detailed description and test program at http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/120052 Attached is the submitted patch, which fixes the issue. Regards Marcus
author Ryan C. Gordon <icculus@icculus.org>
date Mon, 04 Feb 2008 17:22:56 +0000
parents 355632dca928
children
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>SDL_MixAudio</H1
><DIV
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><A
NAME="AEN7107"
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><H2
>Name</H2
>SDL_MixAudio&nbsp;--&nbsp;Mix audio data</DIV
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>Synopsis</H2
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_MixAudio</B
></CODE
>(Uint8 *dst, Uint8 *src, Uint32 len, int volume);</CODE
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><H2
>Description</H2
><P
>This function takes two audio buffers of <TT
CLASS="PARAMETER"
><I
>len</I
></TT
> bytes each
of the playing audio format and mixes them, performing addition, volume
adjustment, and overflow clipping. The <TT
CLASS="PARAMETER"
><I
>volume</I
></TT
> ranges
from 0 to <TT
CLASS="LITERAL"
>SDL_MIX_MAXVOLUME</TT
> and should be set to the maximum
value for full audio volume. Note this does not change hardware volume. This is
provided for convenience -- you can mix your own audio data.</P
><DIV
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><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Do not use this function for mixing together more than two streams of sample
data. The output from repeated application of this function may be distorted
by clipping, because there is no accumulator with greater range than the
input (not to mention this being an inefficient way of doing it).
Use mixing functions from SDL_mixer, OpenAL, or write your own mixer instead.</P
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>See Also</H2
><P
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HREF="sdlopenaudio.html"
><TT
CLASS="FUNCTION"
>SDL_OpenAudio</TT
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