/* ppdis.c, dhq, 06/17/2001.ra
   Mindless hack to disassemble CDC PP programs binary files.
   
   04/09/2023  Updated for modern C and input from `.columntobytes tss.hex > tss.bytes` (prm)
   06/24/2001  Added display code characters column to output.
   06/17/2001  Initial adaption from a program by Francois Pinard
   
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define FATAL 5
#define ASIGN 0400000

//char translated[64];

char bit24[64]={			/* 1 for 24 bit ops */
	0, 1, 1, 0, 0, 0, 0, 0, 
	0, 0, 0, 0, 0, 0, 0, 0,
	1, 1, 1, 1, 0, 0, 0, 0, 
	0, 0, 0, 0, 0, 0, 0, 0, 
	0, 0, 0, 0, 0, 0, 0, 0,
	1, 1, 1, 1, 1, 1, 1, 1, 
	0, 1, 0, 1, 1, 1, 1, 1, 
	0, 1, 0, 1, 0, 0, 0, 1
};


/* //int get_sixbits (arg1) */
/* //FILE	*arg1; */
/* int get_sixbits (FILE	*arg1) */
/*   { */
/*   static int accumulator; */
/*   static int state = 0; */

/*   int byte; */
/*   int sixbit_byte; */

/*   switch (state) */
/*     { */
/*     case 0: */
/*       byte = fgetc (arg1); */
/*       if (byte == EOF) */
/* 	return EOF; */

/*       state = 1; */
/*       sixbit_byte = (byte >> 2) & 0x3f; */
/*       accumulator = byte & 3; */
/*       break; */

/*     case 1: */
/*       byte = fgetc (arg1); */
/*       if (byte == EOF) */
/* 	return EOF; */

/*       state = 2; */
/*       sixbit_byte = (accumulator << 4) | ((byte >> 4) & 0xf); */
/*       accumulator = byte & 0xf; */
/*       break; */

/*     case 2: */
/*       byte = fgetc (arg1); */
/*       if (byte == EOF) */
/* 	return EOF; */

/*       state = 3; */
/*       sixbit_byte = (accumulator << 2) | ((byte >> 6) & 0x3); */
/*       accumulator = byte & 0x3f; */
/*       break; */

/*     case 3: */
/*       state = 0; */
/*       sixbit_byte = accumulator; */
/*       break; */
/*     } */
/*   return sixbit_byte; */
/* } */

int get_sixbits (FILE	*arg1)
  {
  static int accumulator;
  static int state = 0;

  int byte1, byte2;
  int sixbit_byte;

    switch (state)
    {
    case 0:
      byte2 = fgetc (arg1); // little-endian: least significant byte
      if (byte2 == EOF)
	return EOF;
      byte1 = fgetc (arg1); // little-endian: most significant byte
      if (byte1 == EOF)
	return EOF;

      state = 1;
      sixbit_byte = (byte1 >> 2) & 0x3f;
      accumulator = (byte1 & 3) << 4 | ((byte2 >> 4) & 0x0f);
      break;

    case 1:

      state = 0;
      sixbit_byte = accumulator;
      break;
    }
    return sixbit_byte;
}


//main(argc,argv)
// int   argc;
// char *argv[];
int main(int argc, char *argv[])
 {
  int	pp_byte, opHi, opLo, mHi, mLo;
  int	i,wcnt/*,bcnt*/;
  long	checksum;
  //  char	buffer1[21];		/* one byte longer than needed to include room for terminator byte */
  //  int	buffer2[20];          
  FILE	*arg1;
  FILE	*arg2;
  char	translated[65];
  
  short pp, opword, opcode, d, m;
  long dm;


if (argc < 1)   // 2)
 {
   // fputs("Usage :  ppdis <oldfile> <newfile>.  <oldfile> is the name of the file to disassemble.\n"
   //		,stderr);
 fputs("Usage :  ppdis <oldfile> > <newfile>.  <oldfile> is the name of the file to disassemble.\n"
		,stderr);
 exit(FATAL);
 }

if (!(arg1=fopen(argv[1],"rb")))
 {
 fputs("Error - the input file does not exist.\n",stderr);
 exit(FATAL);
 }

//if (!(arg2=fopen(argv[2],"wb")))
// {
// fputs("Error - you must specify the name of the output file.\n",stderr);
// exit(FATAL);
// }

//bcnt = 0;
wcnt = 0; // starting address 0 makes the data and jump addresses match up


/*  Had some stupid problem with the static char const version in this util.  */

    translated[0] = 0x00;
    
    strcat (translated, ":ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");
    strcat (translated, "+-*/()$= ,.#[]%");
    strcat (translated, "\"_!&'?<>@\\^;");
    translated[64] = 0x00;


// for (i=0; i<154; i++)
//    pp_byte = get_sixbits (arg1);
    
// pp_byte = get_sixbits (arg1);
// opword = pp_byte << 6 | get_sixbits (arg1);
// wcnt = opword + 5;

//for (i=0; i<4; i++)
//    pp_byte = get_sixbits (arg1);

/*
for (i=0; i<154; i++)
    pp_byte = get_sixbits (arg1);
wcnt = 16;
*/

while (pp_byte = get_sixbits (arg1), pp_byte != EOF)
     {
     printf ("%4o  ", wcnt);

     opHi = pp_byte;
     opLo = get_sixbits (arg1);
     opword = opHi << 6 | opLo;
     ++wcnt;
     opcode = (opword >> 6) & 077;
     d      = opword & 077;
     if (bit24[opcode])
       {
        mHi = get_sixbits (arg1);
        mLo = get_sixbits (arg1);
        m = mHi << 6 | mLo;
        dm = (((long) d) << 12) | (m & 07777);
        printf ("%02o  %02o  %04o  ", opcode, d, m); 
        fputc(translated[opHi], stdout);
        fputc(translated[opLo], stdout);
        fputc(translated[mHi], stdout);
        fputc(translated[mLo], stdout);
        printf ("            ");
        ++wcnt;
       }
     else
       {
        printf ("%02o  %02o        ", opcode, d);
        fputc(translated[opHi], stdout);
        fputc(translated[opLo], stdout);
        printf ("              ");
       }
     switch (opcode)
       { 
       case 000:				/* pass */
       case 024:
       case 025:
        printf ("PSN");
 	break;
       case 014:				/* load d */
 	printf ("LDN    %02oB", d);
 	break;
       case 015:				/* load complement d */
 	printf ("LCN    %02oB", d);
 	break;
       case 030:				/* load (d) */
        printf ("LDD    %02oB", d);
 	break;
       case 034:				/* store (d) */
        printf ("STD    %02oB", d);
 	break;
       case 040:				/* load ((d)) */
        printf ("LDI    %02oB", d);
 	break;
       case 044:				/* store ((d)) */
        printf ("STI    %02oB", d);
 	break;
       case 020:				/* load dm */
        printf ("LDC    %06loB", dm);
 	break;
       case 050:				/* load (m+(d)) */
        printf ("LDM    %04oB,%02oB", m, d);
 	break;
       case 054:				/* store (m+(d)) */
        printf ("STM    %04oB,%02oB", m, d);
 	break;
       case 016:				/* add d */
        printf ("ADN    %02oB", d);
 	break;
       case 017:				/* subtract d */
        printf ("SBN    %02oB", d);
 	break;
       case 031:				/* add (d) */
        printf ("ADD    %02oB", d);
 	break;
       case 032:				/* subtract (d) */
        printf ("SBD    %02oB", d);
 	break;
       case 041:				/* add ((d)) */
        printf ("ADI    %02oB", d);
 	break;
       case 042:				/* subtract ((d)) */
        printf ("SBI    %02oB", d);
 	break;
       case 021:				/* add dm */
        printf ("ADC    %06loB", dm);
 	break;
       case 051:				/* add (m+(d)) */
        printf ("ADM    %04oB,%02oB", m, d);
 	break;
       case 052:				/* subtract (m+(d)) */	
        printf ("SBM    %04oB,%02oB", m, d);
 	break;
       case 010:				/* shift d */
        printf ("SHN    %02oB", d);
 	break;
       case 011:				/* log diff d */
        printf ("LMN    %02oB", d);
 	break;
       case 012:				/* log prod d */
        printf ("LPN    %02oB", d);
 	break;
       case 013:				/* selective clear d */
        printf ("SCN    %02oB", d);
 	break;
       case 033:				/* log diff (d) */
        printf ("LMD    %02oB", d);
 	break;
       case 043:				/* log diff ((d)) */
        printf ("LMI    %02oB", d);
 	break;
       case 022:				/* log prod dm */
        printf ("LPC    %06loB", dm);
 	break;
       case 023:				/* log diff dm */
        printf ("LMC    %06loB", dm);
 	break;
       case 053:				/* log diff (m+(d)) */
        printf ("LMM    %04oB,%02oB", m, d);
 	break;
       case 035:				/* replace add (d) */
        printf ("RAD    %02oB", d);
 	break;
       case 036:				/* replace add one (d) */
        printf ("AOD    %02oB", d);
 	break;
       case 037:				/* replace subtract one (d) */
        printf ("SOD    %02oB", d);
 	break;
       case 045:				/* replace add ((d)) */
        printf ("RAI    %02oB", d);
 	break;
       case 046:				/* replace add one ((d)) */
        printf ("AOI    %02oB", d);
 	break;
       case 047:				/* replace subtract one ((d)) */
        printf ("SOI    %02oB", d);
 	break;
       case 055:				/* replace add (m+(d)) */
        printf ("RAM    %04oB,%02oB", m, d);
 	break;
       case 056:				/* replace add one (m+(d)) */
        printf ("AOM    %04oB,%02oB", m, d);
	break;
       case 057:				/* replace subtract one (m+(d)) */
        printf ("SOM    %04oB,%02oB", m, d);
 	break;
       case 003:				/* unconditional jump d */
 case003:
        printf ("UJN    %02oB", d);
 	break;
       case 004:				/* zero jump d */
        printf ("ZJN    %02oB", d);
 	break;
       case 005:				/* nonzero jump d */
        printf ("NJN    %02oB", d);
 	break;
       case 006:				/* plus jump d */
        printf ("PJN    %02oB", d);
 	break;
       case 007:				/* minus jump d */
        printf ("MJN    %02oB", d);
 	break;
       case 001:				/* long jump m+(d) */
        printf ("LJM    %04oB,%02oB", m, d);
 	break;
       case 002:				/* return jump m+(d) */
        printf ("RJM    %04oB,%02oB", m, d);
        break;
       case 026:				/* exchange jump */
        printf ("EXN    %02oB", d);
 	break;
       case 027:				/* read program address */
        printf ("RPN    %02oB", d);
 	break;
       case 060:				/* central read from (A) to d */
        printf ("CRD    %02oB", d);
 	break;
       case 061:				/* central read (d) words from (A) to m */ 
        printf ("CRM    %04oB,%02oB", m, d);
 	break;
       case 062:				/* central write to (A) from d */
        printf ("CWD    %02oB", d);
 	break;
       case 063:				/* central write (d) words to (A) from m */
        printf ("CWM    %04oB,%02oB", m, d);
 	break;
       case 064:				/* jump to m if channel d active */
        printf ("AJM    %04oB,%02oB", m, d);
 	break;
       case 065:				/* jump to m if channel d inactive */
        printf ("IJM    %04oB,%02oB", m, d);
 	break;
       case 066:				/* jump to m if channel d full */
        printf ("FJM    %04oB,%02oB", m, d);
 	break;
       case 067:				/* jump to m if channel d empty */
        printf ("EJM    %04oB,%02oB", m, d);
 	break;
       case 070:				/* input to A from channel d */
        printf ("IAN    %02oB", d);
 	break;
       case 071:				/* input (A) words to m from channel d */
        printf ("IAM    %04oB,%02oB", m, d);
 	break;
       case 072:				/* output from A to channel d */
        printf ("OAN    %02oB", d);
 	break;
       case 073:				/* output (A) words from m to channel d */
        printf ("OAM    %04oB,%02oB", m, d);
 	break;
       case 074:				/* activate channel d */
        printf ("ACN    %02oB", d);
 	break;
       case 075:				/* disconnect channel d */
        printf ("DCN    %02oB", d);
 	break;
       case 076:				/* function (A) on channel d */
        printf ("FAN    %02oB", d);
 	break;
       case 077:				/* function m on channel d */
        printf ("FNC    %04oB,%02oB", m, d);
 	break;
       } /* end of opcode switch */

      printf ("\n");
      }
 
  fclose(arg1);
 }