view src/video/xbios/SDL_xbios_sb3.c @ 2042:3908e1f808e1

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 15:56:36 +0000
parents c121d94672cb
children 0e751c1f83f5
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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"

/*
	ScreenBlaster 3 functions

	Patrice Mandin
*/

/*--- Includes ---*/

#include "SDL_stdinc.h"
#include "SDL_xbios.h"
#include "SDL_xbios_sb3.h"

/*--- Defines ---*/

const int SDL_XBIOS_scpn_planes_device[] = {
    SCPN_DEV_1BPP,
    SCPN_DEV_4BPP,
    SCPN_DEV_8BPP,
    SCPN_DEV_16BPP,
    SCPN_DEV_2BPP,
    SCPN_DEV_4BPP,
    SCPN_DEV_1BPP
};

/*--- Functions ---*/

int
SDL_XBIOS_SB3Usable(scpn_cookie_t * cookie_scpn)
{
    scpn_screeninfo_t *scrinfo;
    int bpp;

    /* Check if current SB3 mode is usable, i.e. 8 or 16bpp */
    scrinfo = cookie_scpn->screen_info;
    bpp = 1 << (SDL_XBIOS_scpn_planes_device[scrinfo->device]);

    if ((bpp == 8) || (bpp == 16)) {
        return 1;
    }

    return 0;
}

void
SDL_XBIOS_SB3Init(_THIS, scpn_cookie_t * cookie_scpn)
{
    scpn_screeninfo_t *scrinfo;

    /* SB3 prevent changing video modes, we can only use current one */
    if (XBIOS_modelist) {
        SDL_free(XBIOS_modelist);
        XBIOS_nummodes = 0;
        XBIOS_modelist = NULL;
    }

    scrinfo = cookie_scpn->screen_info;
    scrinfo->h_pos = scrinfo->v_pos = 0;

    SDL_XBIOS_AddMode(this,
                      -1,
                      scrinfo->virtual_width, scrinfo->virtual_height,
                      1 << (SDL_XBIOS_scpn_planes_device[scrinfo->device]),
                      SDL_FALSE);
}

/* vi: set ts=4 sw=4 expandtab: */