fade.c

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/**
 * @file
 * @ingroup graphics
 * @brief Incremental palette transitions, and the DOS string-append shim
 * beside them.
 *
 * Address range 41c510-41c75f. The initialization flag follows the barracks
 * literal pool. Which unit owned DosStrcat is provisional.
 */
#include "wc1.h"
 
#include <sys/types.h>
 
short nPaletteTransitionInitialise = 1; /* 0x00469640 */
short *pPaletteTransDirection; /* 0x005a7d88 */
short *pPaletteTransitionDelta; /* 0x005a7d8c */
short nPaletteTransMaxDelta; /* 0x005a7d90 */
short *pPaletteTransitionAccumulatorPtr; /* 0x005a7d94 */
short nPaletteTransitionCountdown; /* 0x005a7d98 */
 
/* Function start: 0x41C510 */
unsigned short __stdcall StepPaletteTransition(short *current,
                                                const short *target,
                                                short componentCount)
{
    short index;
    short difference;
 
    if (nPaletteTransitionInitialise != 0) {
        pPaletteTransitionAccumulatorPtr =
            AllocateTaggedMemory(componentCount * 2, 0);
        pPaletteTransitionDelta =
            AllocateTaggedMemory(componentCount * 2, 0);
        pPaletteTransDirection =
            AllocateTaggedMemory(componentCount * 2, 0);
        if (pPaletteTransitionAccumulatorPtr == 0 ||
            pPaletteTransitionDelta == 0 ||
            pPaletteTransDirection == 0) {
            if (pPaletteTransitionAccumulatorPtr != 0)
                ReleasePacketHandle(pPaletteTransitionAccumulatorPtr);
            if (pPaletteTransitionDelta != 0)
                ReleasePacketHandle(pPaletteTransitionDelta);
            if (pPaletteTransDirection != 0)
                ReleasePacketHandle(pPaletteTransDirection);
            return 0;
        }
 
        nPaletteTransMaxDelta = 0;
        for (index = 0; index < componentCount; index++) {
            difference = current[index] - target[index];
            if (difference < 0) {
                difference = -difference;
                pPaletteTransDirection[index] = 4;
            } else {
                pPaletteTransDirection[index] = -4;
            }
            pPaletteTransitionDelta[index] = difference;
            if (nPaletteTransMaxDelta < difference)
                nPaletteTransMaxDelta = difference;
        }
 
        difference = nPaletteTransMaxDelta / 4;
        for (index = 0; index < componentCount; index++) {
            pPaletteTransitionAccumulatorPtr[index] = difference;
        }
        nPaletteTransitionInitialise = 0;
        nPaletteTransitionCountdown =
            nPaletteTransMaxDelta / 4;
    }
 
    if (nPaletteTransitionCountdown-- == 0) {
        ReleasePacketHandle(pPaletteTransitionAccumulatorPtr);
        ReleasePacketHandle(pPaletteTransitionDelta);
        ReleasePacketHandle(pPaletteTransDirection);
        nPaletteTransitionInitialise = 1;
        return 0;
    }
 
    for (index = 0; index < componentCount; index++) {
        if ((pPaletteTransitionAccumulatorPtr[index] +=
                 pPaletteTransitionDelta[index]) >
            nPaletteTransMaxDelta) {
            pPaletteTransitionAccumulatorPtr[index] -=
                nPaletteTransMaxDelta;
            current[index] += pPaletteTransDirection[index];
        }
    }
    return 1;
}
 
/* Function start: 0x41C740 */
char *__stdcall DosStrcat(char *destination, const char *source)
{
    char *end;
 
    end = DosStrchr(destination, 0);
    DosStrcpy(end, source);
    return destination;
}