M devices/terminal.c → devices/terminal.c

@@ -2,15 +2,15 @@ #include <stdio.h>
 #include "../xyw.h"
 
 /* terminal device */
-#define terminal_INPUT 0x0
-#define terminal_OUTPUT 0x1
+#define TERMINAL_INPUT 0x0
+#define TERMINAL_OUTPUT 0x1
 
 void terminal_output(xyw_byte *data, xyw_byte addr, xyw_byte *error)
 {
     (void)error;
     switch (addr)
     {
-    case terminal_OUTPUT:
+    case TERMINAL_OUTPUT:
         fputc(data[addr], stdout);
         fflush(stdout);
         break;

M xyw.h → xyw.h

@@ -15,6 +15,7 @@ 
 typedef unsigned char xyw_byte;
 typedef unsigned short xyw_word;
 
+// Device contract
 typedef xyw_byte (*xyw_input)(xyw_byte *data, xyw_byte addr, xyw_byte *error);
 typedef void (*xyw_output)(xyw_byte *data, xyw_byte addr, xyw_byte *error);
 typedef void (*xyw_init)(xyw_byte *data);

M xywrun.c → xywrun.c

@@ -69,9 +69,8 @@ }
 
 static inline xyw_byte get_device_address(xyw_word addr)
 {
-    // Given $FF40, it should return $40
-    // TODO: verify correctness
-    return (xyw_byte)(addr - DEVICE_AREA_START);
+    // Given $FF41, it should return $01
+    return (xyw_byte)((addr - DEVICE_AREA_START) & 0x0F);
 }
 
 //// Read/write memory helpers
@@ -114,14 +113,11 @@ }
 
 static inline void write(xyw_word addr, xyw_byte val)
 {
-    printf("Write to addr=%04X val=%02X\n", addr, val);
     xyw_memory[addr] = val;
     int dev_num = get_device(addr);
-    printf("Device number: %d\n", dev_num);
     if (dev_num >= 0 && xyw_devices[dev_num].output)
     {
         xyw_byte dev_addr = get_device_address(addr);
-        printf("Device address: %02X\n", dev_addr);
         xyw_devices[dev_num].output(get_device_data(addr), dev_addr, error);
     }
 }
@@ -251,7 +247,7 @@ 
 xyw_device xyw_devices[XYW_TOTAL_DEVICES] = {
     // System device (not implemented yet)
     {&xyw_memory[0xff00], 0, 0, 0},
-    // terminal device
+    // Terminal device
     {&xyw_memory[0xff10], 0, 0, terminal_output},
     // Clock device
     {&xyw_memory[0xff20], clock_init, clock_input, 0},