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cc65/samples/sym1/symExtendedMemory.c
2022-04-17 16:06:45 +02:00

102 lines
3.7 KiB
C

// --------------------------------------------------------------------------
// 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 STD_MEM 0x7FFF // Last address of standard memory
#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 );
if ( heap_size > STD_MEM ) {
printf ( "Extended memory already installed.\n" );
} else {
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;
}