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102 lines
3.7 KiB
C
102 lines
3.7 KiB
C
// --------------------------------------------------------------------------
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// Sym-1 Extended Memory
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//
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// Wayne Parham
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//
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// wayne@parhamdata.com
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// --------------------------------------------------------------------------
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//
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// Note: This program examines memory above the monitor ROM (8000-8FFF) to
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// Determine what, if any, memory is available. It then adds whatever
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// 4K segments it finds to the heap.
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//
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// Memory Segment Remark
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// 0x9000 Usually available
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// 0xA000 System I/O, always unavailable
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// 0xB000 Used by RAE, but normally available
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// 0xC000 Used by BASIC, normally unavailable
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// 0xD000 Used by BASIC, normally unavailable
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// 0xE000 Used by RAE, but normally available
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// 0xF000 Normally available, but only to FF7F
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//
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// --------------------------------------------------------------------------
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#include <sym1.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define STD_MEM 0x7FFF // Last address of standard memory
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#define SEGMENT 0x9000 // First 4K segment of extended memory
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#define SEG_END 0x0FFF // Last location of segment
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#define BLOCK_SIZE 0x1000 // Size of segment
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#define TOP_END 0x0F7F // Last location of memory
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#define TOP_SIZE 0x0F80 // Size of top segment
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#define UNAVAILABLE 0xA000 // System I/O area
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int main (void) {
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int error = 0;
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unsigned heap_size = 0x0000;
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char* segment = (char*) SEGMENT;
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printf ( "Analyzing memory.\n\n" );
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heap_size = _heapmemavail();
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printf ( "Main memory has %u bytes available.\n", heap_size );
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if ( heap_size > STD_MEM ) {
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printf ( "Extended memory already installed.\n" );
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} else {
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while ( (int) segment < 0xEFFF ) { // Iterate through 4K memory blocks
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if( (int) segment != UNAVAILABLE ) {
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segment[0] = 0x00; // Check beginning of segment
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if ( segment[0] != 0x00 )
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error = 1;
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segment[0] = 0xFF;
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if ( segment[0] != 0xFF )
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error = 1;
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segment[SEG_END] = 0x00; // Check end of segment
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if ( segment[SEG_END] != 0x00 )
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error = 1;
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segment[SEG_END] = 0xFF;
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if ( segment[SEG_END] != 0xFF )
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error = 1;
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if ( ! error ) { // If memory found, add to the heap
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printf ( "Memory found at location %p, ", segment );
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_heapadd ( segment, BLOCK_SIZE );
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heap_size = _heapmemavail();
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printf( "so the system now has %u bytes available.\n", heap_size );
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} else {
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error = 0;
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}
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}
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segment += 0x1000; // Increment to next segment
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}
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segment[0] = 0x00; // Check beginning of top memory segment
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if ( segment[0] != 0x00 )
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error = 1;
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segment[0] = 0xFF;
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if ( segment[0] != 0xFF )
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error = 1;
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segment[TOP_END] = 0x00; // Check end of usable memory
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if ( segment[TOP_END] != 0x00 )
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error = 1;
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segment[TOP_END] = 0xFF;
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if ( segment[TOP_END] != 0xFF )
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error = 1;
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if ( ! error ) { // If memory found, add to the heap
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printf ( "Memory found at location %p, ", segment );
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_heapadd ( segment, TOP_SIZE );
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heap_size = _heapmemavail();
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printf( "so the system now has %u bytes available.\n", heap_size );
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}
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}
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puts ("\nEnjoy your day!\n");
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return 0;
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}
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