fix GBA ROM header

Populate the GBA ROM header so that emulators and physical Game Boy
Advance consoles recognize the ROM as a valid game.

Note: The reserve space at the end of the header was hand-tuned. Why
this magic value?

targets/gameboy-advance.s

@@ -5,16 +5,48 @@
 
 _start:
     b       start_vector
-    .fill   156,1,0                // Nintendo Logo Character Data (8000004h)
-    .fill   16,1,0                 // Game Title
-    .byte   0x30,0x31              // Maker Code (80000B0h)
-    .byte   0x96                   // Fixed Value (80000B2h)
-    .byte   0x00                   // Main Unit Code (80000B3h)
-    .byte   0x00                   // Device Type (80000B4h)
-    .fill   7,1,0                  // unused
-    .byte   0x00                   // Software Version No (80000BCh)
-    .byte   0xf0                   // Complement Check (80000BDh)
-    .byte   0x00,0x00              // Checksum (80000BEh)
+
+    // ROM header
+    .byte 0x24,0xff,0xae,0x51,0x69,0x9a,0xa2,0x21,0x3d,0x84,0x82,0x0a,0x84,0xe4,0x09,0xad
+    .byte 0x11,0x24,0x8b,0x98,0xc0,0x81,0x7f,0x21,0xa3,0x52,0xbe,0x19,0x93,0x09,0xce,0x20
+    .byte 0x10,0x46,0x4a,0x4a,0xf8,0x27,0x31,0xec,0x58,0xc7,0xe8,0x33,0x82,0xe3,0xce,0xbf
+    .byte 0x85,0xf4,0xdf,0x94,0xce,0x4b,0x09,0xc1,0x94,0x56,0x8a,0xc0,0x13,0x72,0xa7,0xfc
+    .byte 0x9f,0x84,0x4d,0x73,0xa3,0xca,0x9a,0x61,0x58,0x97,0xa3,0x27,0xfc,0x03,0x98,0x76
+    .byte 0x23,0x1d,0xc7,0x61,0x03,0x04,0xae,0x56,0xbf,0x38,0x84,0x00,0x40,0xa7,0x0e,0xfd
+    .byte 0xff,0x52,0xfe,0x03,0x6f,0x95,0x30,0xf1,0x97,0xfb,0xc0,0x85,0x60,0xd6,0x80,0x25
+    .byte 0xa9,0x63,0xbe,0x03,0x01,0x4e,0x38,0xe2,0xf9,0xa2,0x34,0xff,0xbb,0x3e,0x03,0x44
+    .byte 0x78,0x00,0x90,0xcb,0x88,0x11,0x3a,0x94,0x65,0xc0,0x7c,0x63,0x87,0xf0,0x3c,0xaf
+    .byte 0xd6,0x25,0xe4,0x8b,0x38,0x0a,0xac,0x72,0x21,0xd4,0xf8,0x07
+
+    // Game title
+    .byte 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
+
+    // Game code
+    .byte 0x00,0x00,0x00,0x00
+
+    // Maker code
+    .byte 0x00,0x00
+
+    // Fixed value
+    .byte 0x96
+
+    // Main unit code
+    .byte 0x00
+
+    // Device type (0x00 retail, 0x80 debug)
+    .byte 0x00
+
+    // Reserved
+    .byte 0x00,0x00,0x00,0x00,0x00,0x00,0x00
+
+    // Software version
+    .byte 0x00
+
+    // Complement check
+    .byte 0x51
+
+    // Reserved area
+    .space 98
 
 start_vector:
     // Configure stacks