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MC68705R3 simulator with source

Submitted By: WEBMASTER
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#include <stdio.h>
#include "sim.h"

#ifdef MSC
#include <graph.h>
#endif

unsigned char mem[ 4095];

int sim_read( addr)
int addr;
{
int data, done;
char c;
char buff[80];

done = data = 0;
/* Don't prompt user for values if we are disassembling */
if (!disassemble)
{
if (addr >= 0 && addr < 4)
{
   if (mem[addr+4] != 0xFF) /* FF in DDR = all outputs */
   {
c = (char) ((int)'A' + addr);
sprintf(buff, "Enter read value for port %c: ", c);
showprompt( buff);
fgets( buff, 80, stdin);
sscanf( buff, "%d", &data);
   }
   data = data & (~mem[addr+4]) | mem[addr] & mem[addr+4];
   clearline( PROMPTLINE);
   done = 1;
}
else if (addr == AD_REG)
{
   showprompt( "Enter read value for ADC register: ");
   fgets( buff, 80, stdin);
   sscanf( buff, "%d", &data);
   clearline( PROMPTLINE);
   done = 1;
}
}
if (done) goto readend;
if (addr >= 4 && addr < 8)
data = 0xFF; /* port data direction regs are write only */
else if ((addr == TIMER_CONTROL) && (mem[MASK_OPT_REG] & 0x40))
data = (mem[addr] & 0xF7) | 0x37;
else if (addr >= 0 && addr <= 4095)
data = mem[addr];
else if (addr == RW_A)
data = pgm_model.a;
else if (addr == RW_X)
data = pgm_model.x;
else if (addr == RW_SP)
data = pgm_model.sp;
readend:
return(data);
}

int sim_write( addr, data)
int addr, data;
{
if (!disassemble)
{
if (addr >= 0 && addr <= 0x7F) /* permit write to RAM, ports only */
   mem[addr] = data;
else if (addr == RW_A)
   pgm_model.a = data;
else if (addr == RW_X)
   pgm_model.x = data;
else if (addr == RW_SP)
   pgm_model.sp = data;
if (addr == TIMER_CONTROL)
   sim_timer_ctrl();
}
}

int sim_writef( addr, data)
int addr, data;
/* write forced - Just like sim_write but can write to PROM */
/* Called from non-simulation things like 'M' (mem mod) and 'L' (load sx) */
{
if (addr <= 0x7F)
sim_write( addr, data); /* handle special cases, all in RAM, I/O */
else
{
mem[addr] = data; /* Always succeeds - can write to PROM */
}
}

int sim_readf( addr)
int addr;
/* read forced - simply returns mem[addr] - no prompts, no nothing */
/* Used by sim_timer to read TCR as if it were the timer - the user */
/* program cannot read most bits of the TCR in MOR controlled mode */
{
return( mem[addr] );
}

int sim_bitread( addr, bit)
int addr, bit;
/* If bit is an output bit in a port, no need to ask user for value */
/* in that case don't call sim_read, or it would ask */
/* NOTE: returns byte value just like sim_read, not just one bit */
/* The bit argument is only used to check for out bit in port */
/* This is so the trace can show the value of the byte, which */
/* the processor really reads */
{
int data;

if (( addr >= 0 && addr < 4) && (mem[addr+4] & (1<<bit)) )
data = mem[addr];
else
data = sim_read( addr);
return( data);
}

/*********************************************************************/
int load_moto_hex( infile)
FILE *infile;
/* opens infile and reads S0, S1 and S9 records. S0 records are ignored.
S9 records terminate input. Checksums on all records are ignored.
*/
{
int i, j, addr, data, state, count, error, cc, s9;

state = 0;
s9 = 0;

while ( (i = fgetc( infile)) != EOF && !s9)
{
j = (i >= 'A') ? i - 55 : i - '0'; /* if i is hex digit, j is value*/
switch( state)
{
case 0: /* Look for 'S' = beginning of record */
   if (i == 'S')
   {
#ifdef DEBUG
printf( "Found 'S'-");
#endif
state = 1;
count = 0;
cc = 0;
addr = 0;
   }
   break;
case 1: /* Get character after 'S' = record type */
   if (i == '1')
state = 2;
   else if (i == '9')
s9 = 1; /* exit input loop */
   else
state = 0; /* Skip S0 records - look for next 'S' */
   break;
case 2: /* Get byte count for this record */
#ifdef DEBUG
printf( "Count-");
#endif
   count <<= 4;
   count += j;
   cc++;
   if (cc == 2)
   {
#ifdef DEBUG
printf( " Count = %d\n", count);
#endif
state = 3;
addr = 0;
cc = 0;
   }
   break;
case 3: /* Get start address for this record */
#ifdef DEBUG
printf( "Addr-");
#endif
   addr <<= 4;
   addr += j;
   cc++;
   if (cc == 4)
   {
state = 4;
data = 0;
cc = 0;
#ifdef DEBUG
printf( " Addr = %d\n", addr);
#endif
count -= 2;
if (count == 1)
   state = 0; /* Skip checksum, look for 'S' */
   }
   break;
case 4: /* Get data bytes, 2 chars each */
#ifdef DEBUG
printf( "Data-");
#endif
   data <<= 4;
   data += j;
   cc++;
   if (cc == 2)
   {
sim_writef( addr, data);
#ifdef DEBUG
printf( "Wrote %d to %d\n", data, addr);
#endif
addr++;
data = 0;
cc = 0;
count--;
if (count == 1)
   state = 0; /* Skip checksum, look for 'S' */
   }
   break;
} /* end switch */
} /* end while */
return( !s9); /* Error is didn't end with S9 record */
} /* end load_moto_hex */

int load( filename)
char filename[];
/* returns 0 if no error, 1 if error */
{
FILE *infile;
int retval;
char fname[64];
char *cP;
int i;

i = 0;
cP = fname;
while (filename[i] != '\n' && i < 64)
{
if (filename[i] != ' ' && filename[i] != '\x09') /* skip white */
   *cP++ = filename[i];
i++;
}
*cP++ = '\0'; /* Null terminate string */

infile = fopen( fname, "r");
if (infile != NULL)
retval = load_moto_hex( infile);
else
retval = 2;
settextposition( PROMPTLINE,1);
if (retval)
{
if (retval == 2)
   printf ("*** CANNOT OPEN FILE %s ***", fname);
else
   printf( "*** ERROR LOADING FILE %s ***", fname);
}
else
{
printf( "File %s loaded", fname);
sim_reset();
}
promptline_full = 1;
return( retval);
}