// --------------------------------------------------------------------------
// Sym-1 Extended Memory
//
// Wayne Parham
//
// wayne@parhamdata.com
// --------------------------------------------------------------------------
//
// Note:  This  program examines memory above the monitor ROM (8000-8FFF)  to
//        Determine what, if any, memory is available.  It then adds whatever
//        4K segments it finds to the heap.
//
//        Memory Segment     Remark
//            0x9000         Usually available
//            0xA000         System I/O, always unavailable
//            0xB000         Used by RAE, but normally available
//            0xC000         Used by BASIC, normally unavailable
//            0xD000         Used by BASIC, normally unavailable
//            0xE000         Used by RAE, but normally available
//            0xF000         Normally available, but only to FF7F
//
// --------------------------------------------------------------------------

#include <sym1.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define SEGMENT        0x9000          // First 4K segment of extended memory
#define SEG_END        0x0FFF          // Last location of segment
#define BLOCK_SIZE     0x1000          // Size of segment
#define TOP_END        0x0F7F          // Last location of memory
#define TOP_SIZE       0x0F80          // Size of top segment
#define UNAVAILABLE    0xA000          // System I/O area

int main (void) {
   int      error     = 0;
   unsigned heap_size = 0x0000;
   char*    segment   = (char*) SEGMENT;

   printf ( "Analyzing memory.\n\n" );

   heap_size = _heapmemavail();

   printf ( "Main memory has %u bytes available.\n", heap_size );

   while ( (int) segment < 0xEFFF ) {  // Iterate through 4K memory blocks
      if( (int) segment != UNAVAILABLE ) {
         segment[0] = 0x00;            // Check beginning of segment
         if ( segment[0] != 0x00 )
            error = 1;
         segment[0] = 0xFF;
         if ( segment[0] != 0xFF )
            error = 1;
         segment[SEG_END] = 0x00;      // Check end of segment
         if ( segment[SEG_END] != 0x00 )
            error = 1;
         segment[SEG_END] = 0xFF;
         if ( segment[SEG_END] != 0xFF )
            error = 1;
         if ( ! error ) {              // If memory found, add to the heap
            printf ( "Memory found at location %p, ", segment );
            _heapadd ( segment, BLOCK_SIZE );
            heap_size = _heapmemavail();
            printf( "so the system now has %u bytes available.\n", heap_size );
         } else {
            error = 0;
         }
      }
      segment += 0x1000;               // Increment to next segment      
   }

   segment[0] = 0x00;                  // Check beginning of top memory segment
   if ( segment[0] != 0x00 )
      error = 1;
   segment[0] = 0xFF;
   if ( segment[0] != 0xFF )
      error = 1;
   segment[TOP_END] = 0x00;            // Check end of usable memory
   if ( segment[TOP_END] != 0x00 )
      error = 1;
   segment[TOP_END] = 0xFF;
   if ( segment[TOP_END] != 0xFF )
      error = 1;
   if ( ! error ) {                    // If memory found, add to the heap
      printf ( "Memory found at location %p, ", segment );
      _heapadd ( segment, TOP_SIZE );
      heap_size = _heapmemavail();
      printf( "so the system now has %u bytes available.\n", heap_size );
   }

   puts ("\nEnjoy your day!\n");

   return 0;
}