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view src/audio/SDL_mixer_MMX_VC.c @ 4355:9b464226e541 SDL-1.2

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Fixed bug #855 Ludwig Nussel 2009-10-18 06:31:52 PDT an mprotect call was added to fix bug 528. However that results in a buffer that allows writing and code execution. Ie the no-execute security features of modern operating systems are defeated this way. Two mprotect calls are needed. One to make the buffer executable but not writeable when done and another one to make the buffer writeable again if the content needs to be changed.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 18 Oct 2009 17:31:37 +0000
parents a8e5b518e194
children
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#include "SDL_mixer_MMX_VC.h"

#if defined(SDL_BUGGY_MMX_MIXERS) /* buggy, so we're disabling them. --ryan. */
#if ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES)
// MMX assembler version of SDL_MixAudio for signed little endian 16 bit samples and signed 8 bit samples
// Copyright 2002 Stephane Marchesin (stephane.marchesin@wanadoo.fr)
// Converted to Intel ASM notation by Cth
// This code is licensed under the LGPL (see COPYING for details)
// 
// Assumes buffer size in bytes is a multiple of 16
// Assumes SDL_MIX_MAXVOLUME = 128


////////////////////////////////////////////////
// Mixing for 16 bit signed buffers
////////////////////////////////////////////////

void SDL_MixAudio_MMX_S16_VC(char* dst,char* src,unsigned int nSize,int volume)
{
	__asm
	{

		push	edi
		push	esi
		push	ebx
		
		mov		edi, dst		// edi = dst
		mov		esi, src		// esi = src
		mov		eax, volume		// eax = volume
		mov		ebx, nSize		// ebx = size
		shr		ebx, 4			// process 16 bytes per iteration = 8 samples
		jz		endS16
		
		pxor	mm0, mm0
		movd	mm0, eax		//%%eax,%%mm0
		movq	mm1, mm0		//%%mm0,%%mm1
		psllq	mm0, 16			//$16,%%mm0
		por		mm0, mm1		//%%mm1,%%mm0
		psllq	mm0, 16			//$16,%%mm0
		por		mm0, mm1		//%%mm1,%%mm0
		psllq	mm0, 16			//$16,%%mm0
		por		mm0, mm1		//%%mm1,%%mm0			// mm0 = vol|vol|vol|vol

		#ifndef __WATCOMC__
		align	16
		#endif
mixloopS16:
		movq	mm1, [esi]		//(%%esi),%%mm1\n" // mm1 = a|b|c|d
		movq	mm2, mm1		//%%mm1,%%mm2\n" // mm2 = a|b|c|d
		movq	mm4, [esi + 8]	//8(%%esi),%%mm4\n" // mm4 = e|f|g|h
		// pre charger le buffer dst dans mm7
		movq	mm7, [edi]		//(%%edi),%%mm7\n" // mm7 = dst[0]"
		// multiplier par le volume
		pmullw	mm1, mm0		//%%mm0,%%mm1\n" // mm1 = l(a*v)|l(b*v)|l(c*v)|l(d*v)
		pmulhw	mm2, mm0		//%%mm0,%%mm2\n" // mm2 = h(a*v)|h(b*v)|h(c*v)|h(d*v)
		movq	mm5, mm4		//%%mm4,%%mm5\n" // mm5 = e|f|g|h
		pmullw	mm4, mm0		//%%mm0,%%mm4\n" // mm4 = l(e*v)|l(f*v)|l(g*v)|l(h*v)
		pmulhw	mm5, mm0		//%%mm0,%%mm5\n" // mm5 = h(e*v)|h(f*v)|h(g*v)|h(h*v)
		movq	mm3, mm1		//%%mm1,%%mm3\n" // mm3 = l(a*v)|l(b*v)|l(c*v)|l(d*v)
		punpckhwd	mm1, mm2	//%%mm2,%%mm1\n" // mm1 = a*v|b*v
		movq		mm6, mm4	//%%mm4,%%mm6\n" // mm6 = l(e*v)|l(f*v)|l(g*v)|l(h*v)
		punpcklwd	mm3, mm2	//%%mm2,%%mm3\n" // mm3 = c*v|d*v
		punpckhwd	mm4, mm5	//%%mm5,%%mm4\n" // mm4 = e*f|f*v
		punpcklwd	mm6, mm5	//%%mm5,%%mm6\n" // mm6 = g*v|h*v
		// pre charger le buffer dst dans mm5
		movq	mm5, [edi + 8]	//8(%%edi),%%mm5\n" // mm5 = dst[1]
		// diviser par 128
		psrad	mm1, 7			//$7,%%mm1\n" // mm1 = a*v/128|b*v/128 , 128 = SDL_MIX_MAXVOLUME
		add		esi, 16			//$16,%%esi\n"
		psrad	mm3, 7			//$7,%%mm3\n" // mm3 = c*v/128|d*v/128
		psrad	mm4, 7			//$7,%%mm4\n" // mm4 = e*v/128|f*v/128
		// mm1 = le sample avec le volume modifie
		packssdw	mm3, mm1	//%%mm1,%%mm3\n" // mm3 = s(a*v|b*v|c*v|d*v)
		psrad	mm6, 7			//$7,%%mm6\n" // mm6= g*v/128|h*v/128
		paddsw	mm3, mm7		//%%mm7,%%mm3\n" // mm3 = adjust_volume(src)+dst
		// mm4 = le sample avec le volume modifie
		packssdw	mm6, mm4	//%%mm4,%%mm6\n" // mm6 = s(e*v|f*v|g*v|h*v)
		movq	[edi], mm3		//%%mm3,(%%edi)\n"
		paddsw	mm6, mm5		//%%mm5,%%mm6\n" // mm6 = adjust_volume(src)+dst
		movq	[edi + 8], mm6	//%%mm6,8(%%edi)\n"
		add		edi, 16			//$16,%%edi\n"
		dec		ebx				//%%ebx\n"
		jnz mixloopS16

endS16:
		emms
		
		pop		ebx
		pop		esi
		pop		edi
	}

}

////////////////////////////////////////////////
// Mixing for 8 bit signed buffers
////////////////////////////////////////////////

void SDL_MixAudio_MMX_S8_VC(char* dst,char* src,unsigned int nSize,int volume)
{
	_asm
	{

		push	edi
		push	esi
		push	ebx
		
		mov		edi, dst	//movl	%0,%%edi	// edi = dst
		mov		esi, src	//%1,%%esi	// esi = src
		mov		eax, volume	//%3,%%eax	// eax = volume

		movd	mm0, eax	//%%eax,%%mm0
		movq	mm1, mm0	//%%mm0,%%mm1
		psllq	mm0, 16		//$16,%%mm0
		por		mm0, mm1	//%%mm1,%%mm0
		psllq	mm0, 16		//$16,%%mm0
		por		mm0, mm1	//%%mm1,%%mm0
		psllq	mm0, 16		//$16,%%mm0
		por		mm0, mm1	//%%mm1,%%mm0
		
		mov		ebx, nSize	//%2,%%ebx	// ebx = size
		shr		ebx, 3		//$3,%%ebx	// process 8 bytes per iteration = 8 samples
		cmp		ebx, 0		//$0,%%ebx
		je		endS8

		#ifndef __WATCOMC__
		align 16
		#endif
mixloopS8:
		pxor	mm2, mm2	//%%mm2,%%mm2		// mm2 = 0
		movq	mm1, [esi]	//(%%esi),%%mm1	// mm1 = a|b|c|d|e|f|g|h
		movq	mm3, mm1	//%%mm1,%%mm3 	// mm3 = a|b|c|d|e|f|g|h
		// on va faire le "sign extension" en faisant un cmp avec 0 qui retourne 1 si <0, 0 si >0
		pcmpgtb		mm2, mm1	//%%mm1,%%mm2	// mm2 = 11111111|00000000|00000000....
		punpckhbw	mm1, mm2	//%%mm2,%%mm1	// mm1 = 0|a|0|b|0|c|0|d
		punpcklbw	mm3, mm2	//%%mm2,%%mm3	// mm3 = 0|e|0|f|0|g|0|h
		movq	mm2, [edi]	//(%%edi),%%mm2	// mm2 = destination
		pmullw	mm1, mm0	//%%mm0,%%mm1	// mm1 = v*a|v*b|v*c|v*d
		add		esi, 8		//$8,%%esi
		pmullw	mm3, mm0	//%%mm0,%%mm3	// mm3 = v*e|v*f|v*g|v*h
		psraw	mm1, 7		//$7,%%mm1		// mm1 = v*a/128|v*b/128|v*c/128|v*d/128 
		psraw	mm3, 7		//$7,%%mm3		// mm3 = v*e/128|v*f/128|v*g/128|v*h/128
		packsswb mm3, mm1	//%%mm1,%%mm3	// mm1 = v*a/128|v*b/128|v*c/128|v*d/128|v*e/128|v*f/128|v*g/128|v*h/128
		paddsb	mm3, mm2	//%%mm2,%%mm3	// add to destination buffer
		movq	[edi], mm3	//%%mm3,(%%edi)	// store back to ram
		add		edi, 8		//$8,%%edi
		dec		ebx			//%%ebx
		jnz		mixloopS8
		
endS8:
		emms
		
		pop		ebx
		pop		esi
		pop		edi
	}
}

#endif /* SDL_ASSEMBLY_ROUTINES */
#endif /* SDL_BUGGY_MMX_MIXERS */