grom.c

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// Implementation file for GROM data -- note that this only handles the DATA side,
// the emulation side is in main.c.

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <string.h>
#include "main.h"
#include "grom.h"

// pre-init data, used for testing.
extern const unsigned char GROMDATA[];

int GromRead(unsigned char page, unsigned int address) {
	// but this version should be right
	if (page >= GROMPAGES) {
		// out of range
		return -1;
	}

	if (page + GROMSTART >= 8) {
		// this is in the second 64k block
		unsigned int nAddress = ((page+GROMSTART-8)<<13) + address;
		return pgm_read_byte_far((uint32_t)0x10000 + (uint16_t)nAddress);
	} else {
		// this is in the first 64k block
		unsigned int nAddress = ((page+GROMSTART)<<13) + address;
		return pgm_read_byte_near(nAddress);
	}
}

HANDLERS GromHandlers = {
	DummyInit, GromRead, DummyWrite
};