1 files changed, 43 insertions, 0 deletions
diff --git a/emu/7seg.c b/emu/7seg.c
index e69de29..1aaf5f9 100644
--- a/emu/7seg.c
+++ b/emu/7seg.c
@@ -0,0 +1,43 @@
+#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
+	}
+}