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added the character set

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Ghostie 2025-02-10 19:41:12 -05:00
parent fac5c920de
commit 1dbaf0a6ac
3 changed files with 43 additions and 0 deletions
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21
Notes.org
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@ -29,6 +29,27 @@ Chip-8 has a stack that is an array of 16 16-bit values, used to store the
addresses that the Chip8 should return to when returning from a subroutine,
meaning there can be 16 levels of nested subroutines.
*** The Character Set
The Chip8 contains some sprites, called /character set/ which are a group of
sprites representing the hexadecimal digits from 0 to F. They are 5 bytes long
(8x5 pixels). They are stored in the area reserved for Chip8 (0x00-0x1FF).
The following are some examples:
#+begin_src artist
+----+--------+----+ +----+--------+----+
|"0" |Binary |Hex | |"1" |Binary |Hex |
+----+--------+----| +----+--------+----+
|****|11110000|0xF0| | 1 |00100000|0x20|
|* *|10010000|0x90| | 11 |01100000|0x60|
|* *|10010000|0x90| | 1 |00100000|0x20|
|* *|10010000|0x90| | 1 |00100000|0x20|
|****|11110000|0xF0| | 111|01110000|0x70|
+----+--------+----+ +----+--------+----+
#+end_src
** Registers
Chip8 has 16 8-bit data registers, each can hold 1 byte of information.

2
include/config.h
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@ -12,4 +12,6 @@
#define CHIP8_TOTAL_STACK_DEPTH 16
#define CHIP8_TOTAL_KEYS 16
#define CHIP8_CHARACTER_SET_LOAD_ADDRESS 0x00
#endif

20
src/chip8.c
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@ -1,8 +1,28 @@
#include "chip8.h"
#include <memory.h>
const char chip8_default_character_set[] = {
0xf0, 0x90, 0x90, 0x90, 0xf0, // 1
0x20, 0x60, 0x20, 0x20, 0x70, // 2
0xf0, 0x10, 0xf0, 0x80, 0xf0, // 3
0xf0, 0x10, 0xf0, 0x10, 0xf0, // 4
0xf0, 0x80, 0xf0, 0x10, 0xf0, // 5
0xf0, 0x80, 0xf0, 0x90, 0xf0, // 6
0xf0, 0x10, 0x20, 0x40, 0x40, // 7
0xf0, 0x90, 0xf0, 0x90, 0xf0, // 8
0xf0, 0x90, 0xf0, 0x10, 0xf0, // 9
0xf0, 0x90, 0xf0, 0x90, 0x90, // A
0xe0, 0x90, 0xe0, 0x90, 0xe0, // B
0xf0, 0x80, 0x80, 0x80, 0xf0, // C
0xe0, 0x90, 0x90, 0x90, 0xe0, // D
0xf0, 0x80, 0xf0, 0x80, 0xf0, // E
0xf0, 0x80, 0xf0, 0x80, 0x80 // F
};
void
chip8_init (struct chip8 *chip8)
{
memset (chip8, 0, sizeof (struct chip8));
memcpy (&chip8->memory.memory, chip8_default_character_set,
sizeof (chip8_default_character_set));
}