fix #221

Author: mateoconlechuga

examples/gfx_misc/autotester.json

@@ -23,13 +23,13 @@
       "description": "Testing that two rectangles are drawn to the visible screen",
       "start": "vram_start",
       "size": "vram_16_size",
-      "expected_CRCs": [ "5BEF2A9D" ]
+      "expected_CRCs": [ "F15C0070" ]
     },
     "2": {
-      "description": "Testing that there are now four rectangles displayed on the screen",
+      "description": "Testing that there are now four rectangles displayed on the screen, and modified text in the corner",
       "start": "vram_start",
       "size": "vram_16_size",
-      "expected_CRCs": [ "6A171265" ]
+      "expected_CRCs": [ "A9AFBF51" ]
     },
     "3": {
       "description": "Back to the home screen (exit check)",

examples/gfx_misc/src/main.c

@@ -1,9 +1,12 @@
 #include <tice.h>
 #include <graphx.h>
+#include <stdint.h>
 
 /* Main function */
 void main(void) {
 
+    static const uint8_t char_data[8] = { 0xaa, 0x55, 0xff, 0x00, 0xaa, 0x55, 0xff, 0x00 };
+
     /* Start the graphics canvas */
     gfx_Begin();
 
@@ -29,6 +32,10 @@ void main(void) {
     /* Copy the drawn rectangles on the visible screen to the buffer */
     gfx_CopyRectangle(gfx_screen, gfx_buffer, 30, 20, 30, 110, 90, 50);
 
+    /* Attempt to change a character */
+    gfx_SetCharData('a', char_data);
+    gfx_PrintStringXY("aaa", 0, 0);
+
     /* Wait for key input */
     while (!os_GetCSC());
 

src/graphx/graphx.asm

@@ -3576,6 +3576,7 @@ gfx_SetCharData:
 	add	hl,de
 	or	a,a
 	sbc	hl,de			; sets z flag if null
+	ret	z
 	ex	de,hl
 	or	a,a
 	sbc	hl,hl
@@ -3585,7 +3586,7 @@ gfx_SetCharData:
 	add	hl,hl
 	ld	bc,(_TextData)
 	add	hl,bc
-	ret	z
+	ex	de,hl
 	ld	bc,8
 	ldir
 	ret