src/loader/loader_archimedes.c

/*

   Copyright 2021, dettus@dettus.net

   Redistribution and use in source and binary forms, with or without modification,
   are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


 */

// the purpose of this file is to read the MS DOS Game binaries,
// and to translate them into the .mag/.gfx format.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "loader_common.h"
#include "vm68k_macros.h"

#define	READ_INT24LE(ptr,idx)	(\
	(((unsigned int)((ptr)[((idx)+2)])&0xff)<<16)	|\
	(((unsigned int)((ptr)[((idx)+1)])&0xff)<< 8)	|\
	(((unsigned int)((ptr)[((idx)+0)])&0xff)<< 0)	|\
	0)

///////////////////////////////////////////
#define	ADFS_IMAGESIZE	819200
#define	ADFS_NICKMAP_OFFSET	0x40
#define	ADFS_NICKMAP_END	0x400
#define	RECURSIVEMAX	5

typedef	struct _tGames
{
	char magicdirname[10];
	char version;
	char gamename[32];
	unsigned int expectedmask;
	unsigned char pictureorder[32];
} tGames;
#define	MAXGAMES	5
#define	MAXFILENAMENUM	10
#define	F6CODE	6
#define	F7DICT	7
#define	F8STRING2	8
#define	F9STRING1	9
#define	F10PICTURES	10

const tGames loader_archimedes_cGames[MAXGAMES]={
		{"Pawn",		0,"The Pawn",			(1<<F6CODE)|            (1<<F8STRING2)|(1<<F9STRING1)|(1<<F10PICTURES),{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31}},
		{"GUILD",		1,"The Guild of Thieves",	(1<<F6CODE)|(1<<F7DICT)|(1<<F8STRING2)|(1<<F9STRING1)|(1<<F10PICTURES),{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31}},
		{"Jinxter",		2,"Jinxter",			(1<<F6CODE)|(1<<F7DICT)|(1<<F8STRING2)|(1<<F9STRING1)|(1<<F10PICTURES),{16,21,22,11, 0, 6, 3,15,24, 7,12,13, 1,28,26,17,23, 9, 4,18,25,20,10, 8,19,14, 2, 0, 0, 0, 0, 0}},
		{"Corruption",		3,"Corruption",			(1<<F6CODE)|(1<<F7DICT)|(1<<F8STRING2)|(1<<F9STRING1)|(1<<F10PICTURES),{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31}},
		{"Fish!",		3,"Fish!",			(1<<F6CODE)|(1<<F7DICT)|(1<<F8STRING2)|(1<<F9STRING1)|(1<<F10PICTURES),{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31}}
};
int loader_archimedes_findoffset(unsigned char* map,int mapsize,int sectorsize,int indicator,int indlen,int bytespermapbit,int* pStart)
{
	int i;
	int status;
	unsigned int mask;
	unsigned short mapind;
	int sectoroffset;
	int indfound;
	int starti;
	i=0;
	status=0;
	mask=(1<<indlen)-1;

	sectoroffset=0;
	// in case the last 8 bits of the indicator are set, one map entry shares the pointer to several sectors.
	// the last 8 bits are said offset.
	if (indicator&0xff)
	{
		sectoroffset=((indicator&0xff)-1)*sectorsize;
	}
	indicator>>=8;
	indfound=0;
	// go through the allocation map, search for the indicator
	starti=-1;
	while (i<mapsize && indfound==0)
	{
		// TODO: for simplicity reasons, assume that the indicators are byte-aligned within the map.
		// in addition to this, do not think about fragmented files (yet)
		if (status==0)
		{
			mapind=READ_INT16LE(map,i);
			if (mapind)
			{
				if ((mapind&mask)==(indicator))
				{
					indfound=1;
					starti=i;
				}
				if ((mapind&~mask)==0) status=1;
			}
			i+=2;
		} else {
			if (map[i]&0x80)	// byte aligned assumption
			{
				status=0;
			}
			i++;
		}
	}
	if (indfound)
	{
		if (pStart!=NULL)
		{
			*pStart=starti*8*bytespermapbit+sectoroffset;	// this is assuming that the entries are byte-aligned
		}
	}
	return 0;	// did not find the indicator
}
unsigned int loader_archimedes_recursivedir(unsigned char* dskimg,int dsksize,int recursivettl,char* dirname,int hugo0nick1,int sectorsize,int indlen,int bytespermapbit,int diridx, int* pGameId,int *pOffsets,int* pLengths)
{
	int dirsize[2]={0x4cc-5,0x7dd-5};	// Hugo/Nick have different sizes for the directory
	int i;
	int done;
	int retval;
	int found;

	if (recursivettl==-1) return 0;	// too many recursions. something when wrong

	retval=0;
	i=0;
	done=0;
	found=0;
	diridx+=5;	// TODO: check for Hugo/Nick
	while (i<dirsize[hugo0nick1] && !done && retval==0)
	{
		// directories are 16 26 bytes long.
		// 0..9:  10 bytes name
		// 10..13: 4 bytes loadaddr
		// 14..17: 4 bytes execaddr
		// 18..21: 4 bytes length
		// 22..24: 3 bytes indicator
		// 25: 1 byte file type/permissions
		unsigned char name[5];	// looking for filenames F6,F7,F8,F9,F10 requires no more than 4 bytes.
		unsigned int indicator;
		int offset;
		int length;
		unsigned char dirtype;

		name[0]=dskimg[diridx+i+0];	// make upper case
		name[1]=dskimg[diridx+i+1];
		name[2]=dskimg[diridx+i+2];
		name[3]=dskimg[diridx+i+3];
		name[4]=0;

		length=READ_INT32LE(dskimg,diridx+i+18);
		indicator=READ_INT24LE(dskimg,diridx+i+22);
		dirtype=dskimg[diridx+i+25];
		if (name[0]==0) done=1;	// the last entry in the directory starts with 0.
		else {

			if (hugo0nick1)
			{
				loader_archimedes_findoffset(&dskimg[ADFS_NICKMAP_OFFSET],ADFS_NICKMAP_END-ADFS_NICKMAP_OFFSET,sectorsize,indicator,indlen,bytespermapbit,&offset);
			} else {
				offset=indicator<<8;
			}

			if ((dirtype&0x8)==0x8)	// incase it is another directory
			{
				retval=loader_archimedes_recursivedir(dskimg,dsksize,recursivettl-1,(char*)&dskimg[diridx+i+0],hugo0nick1,sectorsize,indlen,bytespermapbit,offset,pGameId,pOffsets,pLengths);
			} else {
				if (name[0]=='F' || name[0]=='f' || name[0]=='c' )	// when the filename starts with an 'f' or 'F'. For "corruption", it is a lower case 'c'. those are the files we are looking for
				{
					int num;	// turn the number behind the F,f, or c into an integer
					num=0;
					if (name[1]>='0' && name[1]<='9')
					{
						num*=10;
						num+=name[1]-'0';
					} else num=-1;
					if (name[2]>='0' && name[2]<='9')
					{
						num*=10;
						num+=name[2]-'0';
					} else if (name[2]!=0xd && name[2]!=0x00) num=-1;
					if (num>=0 && num<=MAXFILENAMENUM)
					{
						pOffsets[num]=offset;
						pLengths[num]=length;
						found|=(1<<num);
					}
				}
			}
		}

		i+=26;
	}
	if (found && *pGameId==-1)
	{
		int j;
		int k;
		int match;

		for (j=0;j<MAXGAMES && *pGameId==-1;j++)
		{
			match=1;
			for (k=0;k<10 && match;k++)
			{
				if (loader_archimedes_cGames[j].magicdirname[k]!=dirname[k] && dirname[k]>' ') match=0;
			}
			if (match)
			{
				*pGameId=j;
			}
		}
		return found;
	}
	return retval;
}
unsigned int loader_archimedes_findfiles(unsigned char* dskimg,int dsksize,
	int *pGameId,int* pOffsets,int* pLengths)		// pOffsets are pointers to the files F6 (code), F7 (dict), f8 (string2), f9(string1), F10 (pictures). IN THAT ORDER. the same goes for the lengths
{
	int hugo0nick1;
	int sectorsize;
	int indlen;
	int bytespermapbit;
	int diridx;
	unsigned int filemask;

	if (dsksize!=ADFS_IMAGESIZE)
	{
		fprintf(stderr,"The diskiamge size is off: %d was expected, but %d bytes were read\n",ADFS_IMAGESIZE,dsksize);
		return LOADER_NOK;
	}

	// step 1: find out, if the disk image contains a file system in the 'Hugo' or 'Nick' format.
	hugo0nick1=-1;
	// do it the lazy way. Just check if at the position where the root directory is expected to be,
	// the magic word "Hugo" or "Nick" appears.
#define	HUGOOFFS 0x400
#define	NICKOFFS 0x800
	// for Hugo disks, this is at the beginning of sector1, so @0x401-0x404
	if (dskimg[HUGOOFFS+1]=='H' && dskimg[HUGOOFFS+2]=='u' && dskimg[HUGOOFFS+3]=='g' && dskimg[HUGOOFFS+4]=='o') hugo0nick1=0;
	// for the Nick disks, this is at the beginning of sector2, so 0x801-0x803
	else if (dskimg[NICKOFFS+1]=='N' && dskimg[NICKOFFS+2]=='i' && dskimg[NICKOFFS+3]=='c' && dskimg[NICKOFFS+4]=='k') hugo0nick1=1;
	else {
		fprintf(stderr,"unable to determine the file system type.\n");
		return LOADER_NOK;
	}
	sectorsize=1024;
	indlen=-1;
	bytespermapbit=-1;
	diridx=0x400;
	// step 2: if it is the "Nick" format, it comes with a header
	if (hugo0nick1==1)
	{
		int rootind;

		// according to //http://www.riscos.com/support/developers/prm/filecore.html#85862
		// the header for the "Nick" format is in the first 36 bytes of the dsk image:
		// since the archimedes had an ARM processor, the values are little endian
		// 0..3: 4 bytes UNKNOWN
		// 4:    1 byte log2sector size  *
		// 5:    1 byte sectors/track
		// 6:    1 bytes heads/track
		// 7:    1 byte density
		// 8:    1 byte indlen           *
		// 9:    1 byte byterspermapbit  *
		// 10:   1 byte skey
		// 11:   1 byte boot option
		// 12:   1 byte lowsector
		// 13:   1 byte number of zones
		// 14:   2 byes zone spare
		// 16:   4 bytes root indicator	*
		// 20:   4 bytes disk size
		// 24:   4 bytes disk id
		// 26..35: disk name
		// only the ones with the * are important

		sectorsize=1<<dskimg[4];
		indlen=dskimg[8];
		bytespermapbit=1<<dskimg[9];
		rootind=READ_INT32LE(dskimg,16);


		loader_archimedes_findoffset(&dskimg[ADFS_NICKMAP_OFFSET],ADFS_NICKMAP_END-ADFS_NICKMAP_OFFSET,sectorsize,rootind,indlen,bytespermapbit,&diridx);
	}


	// at this point, the location of the root directory is known.
	// to find the files named F6, F7, F8, F9, F10, start a recursive search
	filemask=loader_archimedes_recursivedir(dskimg,dsksize,RECURSIVEMAX,"$",	hugo0nick1,sectorsize,indlen,bytespermapbit,diridx,	pGameId,pOffsets,pLengths);

	if (filemask && *pGameId!=-1)
	{
		fprintf(stderr,"loader detected %s --> ",loader_archimedes_cGames[*pGameId].gamename);
		if ((filemask&loader_archimedes_cGames[*pGameId].expectedmask)!=loader_archimedes_cGames[*pGameId].expectedmask)
		{
			fprintf(stderr,"FAIL\n");
			fprintf(stderr,"insufficient files on the disk. sorry\n");
			return LOADER_NOK;
		}
		fprintf(stderr,"okay\n");
		return LOADER_OK;
	}
	return LOADER_NOK;

}
int loader_archimedes_mkmag(unsigned char *dskimg,int dsksize,unsigned char* magbuf,int* magsize,
		int gameId,int* offsets,int *lengths)
{
	int magidx;
	int codesize;
	int string1size;
	int string2size;
	int dictsize;

	magidx=42;
	// the game code is stored in F6, it is packed
	codesize=loader_common_unhuffer(&dskimg[offsets[F6CODE]],lengths[F6CODE],&magbuf[magidx]);
	magidx+=codesize;
	// the string1 is stored in F9
	memcpy(&magbuf[magidx],&dskimg[offsets[F9STRING1]],lengths[F9STRING1]);
	string1size=lengths[F9STRING1];
	magidx+=string1size;
	// string2 is in F8, it is packed
	string2size=loader_common_unhuffer(&dskimg[offsets[F8STRING2]],lengths[F8STRING2],&magbuf[magidx]);
	magidx+=string2size;
	if (loader_archimedes_cGames[gameId].version)	// the pawn did not have a dictionary file.
	{
		// the dict is stored in F7, it is packed
		dictsize=loader_common_unhuffer(&dskimg[offsets[F7DICT]],lengths[F7DICT],&magbuf[magidx]);
		magidx+=dictsize;
	} else {
		dictsize=0;
	}

	loader_common_addmagheader(magbuf,magidx,loader_archimedes_cGames[gameId].version,codesize,string1size,string2size,dictsize,-1);

	*magsize=magidx;

	return LOADER_OK;
}
// the archimedes basically uses the same graphic format as the Amiga and the Atari.
// all that is needed is to find the offsets to the pictures.
int loader_archimedes_mkgfx(unsigned char *dskimg,int dsksize,unsigned char* gfxbuf,int* gfxsize,
		int gameId,int* offsets,int *lengths)
{

	int gfxcnt;
	int idx;
	// TODO: since the memory is shared, make sure that offsets[10]>260!!!
	gfxbuf[0]='M';gfxbuf[1]='a';gfxbuf[2]='P';gfxbuf[3]='i';
	WRITE_INT32BE(gfxbuf,4,*gfxsize);
	idx=offsets[F10PICTURES];
	gfxcnt=0;
	while (idx<(offsets[F10PICTURES]+lengths[F10PICTURES]-48))
	{
		// i do not know where the index for the pictures is.
		// their format is as followed: there is a 48 byte header. then comes the picture data.
		// luckily, within this header, at position 0x10, there is a magic sequece 00 00 07 77.
		// that is sufficient to find the end of the header, and consequently, the beginning of the picture data.

		if (dskimg[idx+0x10]==0x00 && dskimg[idx+0x11]==0x00 && dskimg[idx+0x12]==0x07 && dskimg[idx+0x13]==0x77)
		{
			WRITE_INT32BE(gfxbuf,4*loader_archimedes_cGames[gameId].pictureorder[gfxcnt]+8,idx+48);
			gfxcnt++;
		}
		idx++;
	}
	return LOADER_OK;
}

int loader_archimedes(char* filename,char* magbuf,int* magsize,char* gfxbuf,int* gfxsize)
{
	FILE *f;
	int newgfxsize;
	int offsets[MAXFILENAMENUM+1]={0};
	int lengths[MAXFILENAMENUM+1]={0};
	int gameId=-1;


	// read the input file.
	// actually, use the gfx buffer for that one. the data will be read linearly, the
	// pictures are already in the GFX1 format. all that is needed is a header and
	// an index.
	newgfxsize=*gfxsize;
	f=fopen(filename,"rb");
	newgfxsize=fread(gfxbuf,sizeof(char),newgfxsize,f);
	fclose(f);


	if (loader_archimedes_findfiles((unsigned char*)gfxbuf,newgfxsize,&gameId,offsets,lengths)!=LOADER_OK)
	{
		return LOADER_NOK;
	}

	// since the data is in the gfx buf, we need to generate the magbuf first.
	if (loader_archimedes_mkmag((unsigned char*)gfxbuf,newgfxsize,(unsigned char*)magbuf,magsize, gameId,offsets,lengths)!=LOADER_OK)
	{
		return LOADER_NOK;
	}
	// now all the relevant data from the gfxbuf has been read, it is okay to overwrite it.
	if (loader_archimedes_mkgfx((unsigned char*)gfxbuf,newgfxsize,(unsigned char*)gfxbuf,gfxsize, gameId,offsets,lengths)!=LOADER_OK)
	{
		return LOADER_NOK;
	}

	*gfxsize=newgfxsize;
	return LOADER_OK;
}