opl2to4

opl2to4.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>

/*
    convert opl2 commands to opl4 commands
*/

void cni(uint8_t** dest, void* src, int size)
{
    memcpy(*dest,src,size);
    *dest += size;
}
int main(int argc, char* argv [])
{
    if(argc<2)
    {
        printf("Usage: <file> <destination file>\n");
        exit(EXIT_FAILURE);
    }

    char* file1 = argv[1];

    char* file2 = argv[1];
    if(argv[2] != NULL)
        file2 = argv[2];

    int res;
    FILE* sourcefile;

    sourcefile = fopen(file1,"rb");
    if(!sourcefile)
    {
        printf("Could not open %s\n",file1);
        exit(EXIT_FAILURE);
    }
    fseek(sourcefile,0,SEEK_END);

    unsigned long sourcefile_size = ftell(sourcefile);

    rewind(sourcefile);

    uint8_t* source = (uint8_t*)malloc(sourcefile_size);
    uint8_t* dest = (uint8_t*)malloc(sourcefile_size*2);

    res = fread(source,1,sourcefile_size,sourcefile);
    if(res != sourcefile_size)
    {
        printf("Reading error\n");
        exit(EXIT_FAILURE);
    }
    fclose(sourcefile);
    /////////////////////////////////////////////////////////

    uint8_t *srcptr, *destptr = dest, *looppos = source, *endptr = source+sourcefile_size-5;
    int chipcommands = 0, chip2commands = 0, endofdata = 0;
    unsigned long i;
    int channel=0, addr=0, value=0, badflag=0, badchannel=0;

    looppos += (*(uint32_t*)(source+0x1c)) + 0x1c;
    srcptr = source + (*(uint32_t*)(source+0x34)) + 0x34;

    int cpsize=srcptr-source, skip;

    cni(&destptr,source,cpsize);
	
	uint8_t expansion_reg = 0;

    while((srcptr < endptr) && !endofdata)
    {
        if(srcptr == looppos)
            *(uint32_t*)(dest+0x1c) = (destptr-dest)-0x1c;

        uint8_t d = (*srcptr);
        uint8_t cmd = *(srcptr+1);
		uint8_t data1 = *(srcptr+2);
		uint8_t data2 = *(srcptr+3);

		//printf("%08x = %02x, %08x\n",srcptr-source,d,destptr-dest);
        if(d==0x66)
            endofdata = 1;
	    else if(d==0x5a || d==0x5e || d==0x5f)
        {
			*destptr++ = 0xd0;
			*destptr++ = d==0x5f ? 0x01 : 0x00;
			if(cmd == 0x05)
			{
				expansion_reg |= data1;
				*destptr++ = 0x05;
				*destptr++ = expansion_reg;
				//printf("Expansion reg: %02x\n",expansion_reg);
			}
			else
				cni(&destptr,srcptr+1,2);
            srcptr+=3;
			chipcommands++;
        }
		else if(d==0xd0)
		{
			if(cmd < 0x02 && data1 == 0x05)
			{
				expansion_reg |= data2;
				*destptr++ = 0xd0;
				*destptr++ = 0x00;
				*destptr++ = 0x05;
				*destptr++ = expansion_reg;
				//printf("Expansion reg: %02x\n",expansion_reg);
			}
            else
				cni(&destptr,srcptr,4);
            srcptr+=4;
			chip2commands++;
		}
        else if (d==0x67)
        {
            skip = *(uint32_t*)(srcptr+3) & 0x0FFFFFFF;
            cni(&destptr,srcptr,skip+7);
            srcptr += skip+7;
        }
        else if(d == 0x4f || d == 0x50 || (d>=0x30 && d<0x40))
        {
            cni(&destptr,srcptr,2);
            srcptr+=2;
        }
        else if((d>0x50 && d<0x62) || (d>=0xa0 && d<0xc0))
        {
            cni(&destptr,srcptr,3);
            srcptr+=3;
        }
        else if(d>=0xc0 && d<0xe0)
        {
            cni(&destptr,srcptr,4);
            srcptr+=4;
        }
        else if(d>=0xe0 && d<0xe3)
        {
            cni(&destptr,srcptr,5);
            srcptr+=5;
        }
        else
        {
            cni(&destptr,srcptr,1);
            srcptr++;
        }
    }
    printf("changed %d OPL2/OPL3 commands, %d OPL4 commands\n",chipcommands,chip2commands);

    *(uint32_t*)(dest+0x60) = 33868800;

    uint32_t id3offset = *(uint32_t*)(source+0x14);
    if(id3offset>0)
        *(uint32_t*)(dest+0x14) = (destptr-dest)-0x13;

    cni(&destptr,srcptr, sourcefile_size-(srcptr-source));
    *(uint32_t*)(dest+0x04) = (destptr-dest)-0x04;

    FILE *destfile;
    destfile = fopen(file2,"wb");
    if(!destfile)
    {
        printf("Could not open %s\n",file2);
        exit(EXIT_FAILURE);
    }
    for(i=0;i<(destptr-dest);i++)
    {
        putc(*(dest+i),destfile);
    }
    fclose(destfile);
    printf("wrote %lu bytes to %s\n",i,file2);

    free(dest);
    free(source);
}