palette.c

/*****************************************************************************

Copyright (c) 2022  Michal Necasek

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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The above copyright notice and this permission notice shall be included in
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*****************************************************************************/

/* Display driver palette (RAMDAC) functions. */

#include "winhack.h"
#include <gdidefs.h>
#include <dibeng.h>
#include "minidrv.h"
#include <conio.h>      /* For port I/O prototypes. */
#include "boxvint.h"    /* For VGA register definitions. */


/* Load the VGA DAC with values from color table. */
static void SetRAMDAC( UINT bStart, UINT bCount, RGBQUAD FAR *lpPal )
{
    BYTE    bIndex = bStart;

    /* The data format is too weird for BOXV_dac_set(). Do it by hand. */
    outp( VGA_DAC_W_INDEX, bIndex );    /* Set starting index. */
    while( bCount-- ) {
        outp( VGA_DAC_DATA, lpPal[bIndex].rgbRed );
        outp( VGA_DAC_DATA, lpPal[bIndex].rgbGreen );
        outp( VGA_DAC_DATA, lpPal[bIndex].rgbBlue );
        ++bIndex;
    }
}

/* Allow calls from the _INIT segment. */
void __far SetRAMDAC_far( UINT bStart, UINT bCount, RGBQUAD FAR *lpPal )
{
    SetRAMDAC( bStart, bCount, lpPal );
}

UINT WINAPI __loadds SetPalette( UINT wStartIndex, UINT wNumEntries, LPVOID lpPalette )
{
    /* Let the DIB engine do what it can. */
    DIB_SetPaletteExt( wStartIndex, wNumEntries, lpPalette, lpDriverPDevice );

    if( !(lpDriverPDevice->deFlags & BUSY) )
        SetRAMDAC( wStartIndex, wNumEntries, lpColorTable );

    return( 0 );
}