0xff for unmapped regions

coder114514 · coder114514 · commit 6154b17e8fa8 · 2024-03-10T15:17:00.000+08:00
diff --git a/emulator/src/Chipset/MMU.cpp b/emulator/src/Chipset/MMU.cpp
@@ -145,13 +145,13 @@ namespace casioemu {
         MemoryByte *segment = segment_dispatch[segment_index];
         if (!segment) {
             emulator.HandleMemoryError();
-            return 0;
+            return 0xFF;
         }
 
         MMURegion *region = segment[segment_offset].region;
         if (!region) {
             emulator.HandleMemoryError();
-            return 0;
+            return 0xFF;
         }
 
         return (((uint16_t)region->read(region, offset + 1)) << 8) | region->read(region, offset);
@@ -167,7 +167,7 @@ namespace casioemu {
         MemoryByte *segment = segment_dispatch[segment_index];
         if (!segment) {
             emulator.HandleMemoryError();
-            return 0;
+            return 0xFF;
         }
 
         MemoryByte &byte = segment[segment_offset];
@@ -182,7 +182,7 @@ namespace casioemu {
         }
         if (!region) {
             emulator.HandleMemoryError();
-            return 0;
+            return 0xFF;
         }
 
         return region->read(region, offset);

Original file line number	Diff line number	Diff line change
`@@ -145,13 +145,13 @@ namespace casioemu {`
`145`	`145`	`MemoryByte *segment = segment_dispatch[segment_index];`
`146`	`146`	`if (!segment) {`
`147`	`147`	`emulator.HandleMemoryError();`
`148`		`- return 0;`
	`148`	`+ return 0xFF;`
`149`	`149`	`}`
`150`	`150`
`151`	`151`	`MMURegion *region = segment[segment_offset].region;`
`152`	`152`	`if (!region) {`
`153`	`153`	`emulator.HandleMemoryError();`
`154`		`- return 0;`
	`154`	`+ return 0xFF;`
`155`	`155`	`}`
`156`	`156`
`157`	`157`	`return (((uint16_t)region->read(region, offset + 1)) << 8) \| region->read(region, offset);`
`@@ -167,7 +167,7 @@ namespace casioemu {`
`167`	`167`	`MemoryByte *segment = segment_dispatch[segment_index];`
`168`	`168`	`if (!segment) {`
`169`	`169`	`emulator.HandleMemoryError();`
`170`		`- return 0;`
	`170`	`+ return 0xFF;`
`171`	`171`	`}`
`172`	`172`
`173`	`173`	`MemoryByte &byte = segment[segment_offset];`
`@@ -182,7 +182,7 @@ namespace casioemu {`
`182`	`182`	`}`
`183`	`183`	`if (!region) {`
`184`	`184`	`emulator.HandleMemoryError();`
`185`		`- return 0;`
	`185`	`+ return 0xFF;`
`186`	`186`	`}`
`187`	`187`
`188`	`188`	`return region->read(region, offset);`