Fixed gfx_SetCharData for NULL inputs (issue #619). Also added an extra example for gfx_SetCharData

Author: ZERICO2005

examples/library_examples/graphx/text_custom/autotest.json

@@ -16,7 +16,11 @@
     "key|enter",
     "hashWait|2",
     "key|enter",
-    "hashWait|3"
+    "hashWait|3",
+    "key|enter",
+    "hashWait|4",
+    "key|enter",
+    "hashWait|5"
   ],
   "hashes":
   {
@@ -25,16 +29,30 @@
       "description": "Test custom font display",
       "start": "vram_start",
       "size": "vram_8_size",
-      "expected_CRCs": [ "F717BF65" ]
+      "expected_CRCs": [ "711E0ED5" ]
     },
     "2":
     {
-      "description": "Test hidden font display",
+      "description": "Before: ***",
       "start": "vram_start",
       "size": "vram_8_size",
-      "expected_CRCs": [ "EDA09A59" ]
+      "expected_CRCs": [ "1BD16129" ]
     },
     "3":
+    {
+      "description": "After:  ***",
+      "start": "vram_start",
+      "size": "vram_8_size",
+      "expected_CRCs": [ "B090D407" ]
+    },
+    "4":
+    {
+      "description": "Test hidden font display",
+      "start": "vram_start",
+      "size": "vram_8_size",
+      "expected_CRCs": [ "0170C971" ]
+    },
+    "5":
     {
       "description": "Test program exit",
       "start": "vram_start",

examples/library_examples/graphx/text_custom/src/main.c

@@ -9,8 +9,6 @@ static unsigned char font8x8_spacing[128];
 
 int main(void)
 {
-    int i;
-
     /* Initialize graphics drawing */
     gfx_Begin();
 
@@ -24,15 +22,30 @@ int main(void)
     /* Waits for a key */
     while (!os_GetCSC());
 
+    PrintCentered("Before: ***");
+
+    /* Waits for a key */
+    while (!os_GetCSC());
+
+    /* Get a pointer to the character data for '*' by passing in NULL */
+    unsigned char *char_ptr = gfx_SetCharData('*', NULL);
+
+    /* Invert the pixels of '*' */
+    for (int i = 0; i < 8; i++) {
+        char_ptr[i] = ~char_ptr[i];
+    }
+
+    PrintCentered("After:  ***");
+
+    /* Waits for a key */
+    while (!os_GetCSC());
+
     /* Change the font by shifting each character up 1 */
-    for (i = 127; i > 0; --i)
+    for (int i = 127; i > 0; --i)
     {
         gfx_SetCharData(i, &font8x8[(i - 1) * 8]);
     }
 
-    /* Clear old string */
-    gfx_FillScreen(255);
-
     /* Print with the changed font */
     PrintCentered("Uijt!tusjoh!xbt!ijeefo\"");
 
@@ -48,9 +61,12 @@ int main(void)
 /* Prints a screen centered string */
 void PrintCentered(const char *str)
 {
-    gfx_PrintStringXY(str,
-                      (GFX_LCD_WIDTH - gfx_GetStringWidth(str)) / 2,
-                      (GFX_LCD_HEIGHT - 8) / 2);
+    /* Clear old string */
+    gfx_FillScreen(255);
+
+    int x_center = (GFX_LCD_WIDTH - gfx_GetStringWidth(str)) / 2;
+    int y_center = (GFX_LCD_HEIGHT - 8) / 2;
+    gfx_PrintStringXY(str, x_center, y_center);
 }
 
 static unsigned char font8x8_spacing[128] =
@@ -181,7 +197,7 @@ static unsigned char font8x8[128 * 8] =
 	0x00, 0x00, 0x00, 0x7e, 0x46, 0x62, 0x62, 0x7e,	// Char 111 (o)
 	0x00, 0x00, 0x00, 0x7e, 0x46, 0x42, 0x7e, 0x60,	// Char 112 (p)
 	0x60, 0x00, 0x00, 0x7e, 0x46, 0x42, 0x7e, 0x02,	// Char 113 (q)
-	0x02, 0x00, 0x00, 0x7e, 0x46, 0x60, 0x60, 0x60,	// Char 114 (r)
+	0x00, 0x00, 0x00, 0x7e, 0x46, 0x60, 0x60, 0x60,	// Char 114 (r)
 	0x00, 0x00, 0x00, 0x7c, 0x40, 0x7c, 0x04, 0x7c,	// Char 115 (s)
 	0x00, 0x10, 0x10, 0x3c, 0x10, 0x10, 0x18, 0x1c,	// Char 116 (t)
 	0x00, 0x00, 0x00, 0x46, 0x46, 0x62, 0x62, 0x7e,	// Char 117 (u)

src/graphx/graphx.asm

@@ -4018,25 +4018,24 @@ gfx_SetCharData:
 ;  arg0 : Pointer to character data; if null returns current data
 ; Returns:
 ;  Pointer to character data if null, otherwise pointer to next character
-	ld	iy,0
-	add	iy,sp
-	ld	hl,(iy+6)		; de -> custom character data
-	add	hl,de
-	or	a,a
-	sbc	hl,de			; sets z flag if null
+	ld	iy, 0
+	add	iy, sp
+	sbc	hl, hl		; ld hl, 0
+	ld	de, (iy + 6)	; de -> custom_character_data
+	sbc	hl, de		; sets z flag if NULL
+	add	hl, de
+	ld	l, (iy + 3)	; hl = index
+	add	hl, hl
+	add	hl, hl
+	add	hl, hl
+	ld	bc, (_TextData)
+	add	hl, bc
+	; returns _TextData + (index * 8) if custom_character_data is NULL
 	ret	z
-	ex	de,hl
-	or	a,a
-	sbc	hl,hl
-	ld	l,(iy+3)		; hl = index
-	add	hl,hl
-	add	hl,hl
-	add	hl,hl
-	ld	bc,(_TextData)
-	add	hl,bc
-	ex	de,hl
-	ld	bc,8
+	ld	bc, 8
+	ex	de, hl
 	ldir
+	; returns custom_character_data + 8
 	ret
 
 ;-------------------------------------------------------------------------------