Commander X16

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void DirectMemoryAccess(unsigned char DataBus, unsigned int destination, unsigned char stride, volatile unsigned char* Source, unsigned char ByteCount) {
    ADDRx_L = destination & 0xFF;                              // Low Byte of destination sent to $9f20
    ADDRx_M = (destination >> 8) & 0xFF;                       // High Byte of destination sent to $9f21
    ADDRx_H = ((destination >> 16) & 0x01) | (stride << 4);    // destination overflow bit sent to bit zero of $9f22. Stride sent to high nibble.

    switch(DataBus) {
        case 0:
            CTRL = CTRL & ~0x01;                                // Bit 0 of $9f25 set to zero for DataBus 0
            for(unsigned char i = 0; i < ByteCount; i++) {
                DATA_0 = *(Source + i);                         // Copy Data from RAM to VRAM.
            }
            break;
        case 1:
            CTRL = (CTRL & ~0x01) | 0x01;                       // Bit zero of $9f5 set to one for DataBus 1.
            for(unsigned char i = 0; i < ByteCount; i++) {
                DATA_1 = *(Source + i);                         // Copy Data from RAM to VRAM.
            }
            break;
    }
}