emu/7seg.c


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#include "7seg.h"

#include <stdio.h>

void seg7_init( seg7_t *seg )
{
	seg->debug = false;
}

uint8_t seg7_read( seg7_t *seg, uint16_t addr )
{
	return 0;
}

void seg7_write( seg7_t *seg, uint16_t addr, uint8_t data )
{
	switch( addr ) {
		case DDRA:
			seg->ddr = data;
			break;
		
		case PORTA:
			// write bits from SER into shift register on positive SRCLK
			if( ( seg->ddr | ( SRCLK & SER ) ) && ( data & SRCLK ) ) {
				seg->shift = ( seg->shift << 1 ) | ( data & SER );
				if( seg->debug ) {
					fprintf( stderr, "7seg shifting data, data is now %02X\n", seg->shift );
				}
			}
			
			// copy shift to latch register on positive RCLK
			if( ( seg->ddr | RCLK ) && ( data & RCLK ) ) {
				seg->latch = seg->shift;
				if( seg->debug ) {
					fprintf( stderr, "7seg copying %02X from shift to latch\n", seg->latch );
				}
			}
			
			break;
		
		// ignore writes to other addresses
	}
}