The document discusses a PHP implementation of a Game Boy emulator that runs in the terminal. It explains how the emulator works, including how it simulates the Game Boy's CPU, memory, display, sound, buttons and communication port in PHP code. It provides code examples for emulating the CPU instructions and reading button input from the keyboard.

1. Reading
php-terminal-gameboy-emulator
Digital Circus, Inc.
HASEGAWA Tomki

2. HASEGAWA Tomoki
@tomzoh
Web / iOS App Development,
Rental Kart Race, Beer, IoT crafting, …
hasegawa
tomoki
Digital Circus, Inc. Vice-master CTO
Tokyo, Japan
Interests

3. ・ Web Development
・ Mobile Apps Development
・ Service
（ ）
（iOS, Android)
（http://appbuilder.jp）
Twitter: @tomzoh

4. Twitter: @tomzoh

5. Today’s theme
Reading
php-terminal-gameboy-emulator

6. Today’s theme
Reading
php-terminal-gameboy-emulator

7. By Transfrom JPEG version and remove white background. Original by Evan-Amos. - Media:Game-Boy-FL.jpg,
Public Domain, https://commons.wikimedia.org/w/index.php?curid=37808150

8. 23, February

12. 😮

13. 😮

14. 😮
Awesome!!

15. 😮
Awesome!!
Waste of talent!!

16. 😮
Awesome!!
Waste of talent!! Cool!!

17. Source Files

18. Source Files
It’s PHP !

19. Source Files
It’s PHP !
We can read it.

20. Source Files
It’s PHP !
Yes, We can!
We can read it.

21. Source Files
It’s PHP !
Yes, We can!
Yes, We can!
We can read it.

22. Today’s theme
Reading
php-terminal-gameboy-emulator

23. Components of GAMEBOY
• CPU / Memory
• Display
• Sound
• Buttons
• Communication Port

24. Components of GAMEBOY
• CPU / Memory
• Display
• Sound
• Buttons
• Communication Port

25. Buttons

28. Buttons - Keyboard.php
<?php
namespace GameBoy;
class Keyboard
{
public $core;
public $file;
public $keyPressing = null;
public $started = false;
public function __construct(Core $core)
{
$this->core = $core;
exec('stty -icanon');
$this->file = fopen('php://stdin', 'r');
stream_set_blocking($this->file, false);
}
public function check()
{

29. Buttons - Keyboard.php
<?php
namespace GameBoy;
class Keyboard
{
public $core;
public $file;
public $keyPressing = null;
public $started = false;
public function __construct(Core $core)
{
$this->core = $core;
exec('stty -icanon');
$this->file = fopen('php://stdin', 'r');
stream_set_blocking($this->file, false);
}
public function check()
{

30. How to sense buttons

31. How to sense buttons
$this->file = fopen('php://stdin', 'r');

32. How to sense buttons
$this->file = fopen('php://stdin', 'r');
$key = fread($this->file, 1);

33. Simple

34. CPU / Memory

35. CPU

36. SHARP LR35902 instruction set
http://www.pastraiser.com/cpu/gameboy/gameboy_opcodes.html
1byte instructions Prefix CB instructions
144 instructions 256 instructions+
= 400 instructions

37. SHARP LR35902 resistors
http://www.pastraiser.com/cpu/gameboy/gameboy_opcodes.html
15 … 8 7 … 0
A F
B C
H L
15 … 8 7 … 0
SP (Stack Pointer)
PC (Program Counter)
8bit / 16bit resistors
16bit resistors
Flag registor
7 6 5 4 3 2 1 0
Z N H C 0 0 0 0
•Z - Zero Flag
•N - Subtract Flag
•H - Half Carry Flag
•C - Carry Flag
•0 - Not uses, always zero

38. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -

39. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Length in bytes
Address
LD A, d8
2 8
- - - -

40. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Duration in cyclesLength in bytes
Address
LD A, d8
2 8
- - - -

41. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Duration in cycles
Flags affected
Length in bytes
Address
LD A, d8
2 8
- - - -

42. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -

43. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
PC (Program Counter)

44. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Load 0x0301 into BC resistor
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
PC (Program Counter)

45. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
PC (Program Counter)

46. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
Load 0x99 into A resistor
PC (Program Counter)

47. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
PC (Program Counter)

48. Instruction in memory
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Load A resistor’s value into memory
indicates with BC resistor
x0 x1 x2 xE
0x 3x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Address
LD A, d8
2 8
- - - -
PC (Program Counter)

51. CPU - Opcode.php
<?php
namespace GameBoy;
class Opcode
{
public $functionsArray = [];
public function __construct()
{
//NOP
//#0x00:
$this->functionsArray[] = function ($parentObj) {
//Do Nothing...
};
//LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {

52. CPU - Opcode.php
<?php
namespace GameBoy;
class Opcode
{
public $functionsArray = [];
public function __construct()
{
//NOP
//#0x00:
$this->functionsArray[] = function ($parentObj) {
//Do Nothing...
};
//LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
x0 x1 x2
0x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -

53. CPU - Opcode.php
<?php
namespace GameBoy;
class Opcode
{
public $functionsArray = [];
public function __construct()
{
//NOP
//#0x00:
$this->functionsArray[] = function ($parentObj) {
//Do Nothing...
};
//LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
Implementation of 0x00 NOP
x0 x1 x2
0x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -

54. CPU - Opcode.php
<?php
namespace GameBoy;
class Opcode
{
public $functionsArray = [];
public function __construct()
{
//NOP
//#0x00:
$this->functionsArray[] = function ($parentObj) {
//Do Nothing...
};
//LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
x0 x1 x2
0x
LD BC, d16
3 12
- - - -
NOP
1 4
- - - -
LD (BC), A
1 8
- - - -
Implementation of 0x01 LD BC, d16

55. //LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
$parentObj->registerC =
$parentObj->memoryReader[$parentObj->programCounter]($parentObj, $parentObj->programCounter);
$parentObj->registerB =
$parentObj->memoryRead(($parentObj->programCounter + 1) & 0xFFFF);
$parentObj->programCounter = ($parentObj->programCounter + 2) & 0xFFFF;
};
Implementation of LD BC, d16
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Address
PC (Program Counter)

56. //LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
$parentObj->registerC =
$parentObj->memoryReader[$parentObj->programCounter]($parentObj, $parentObj->programCounter);
$parentObj->registerB =
$parentObj->memoryRead(($parentObj->programCounter + 1) & 0xFFFF);
$parentObj->programCounter = ($parentObj->programCounter + 2) & 0xFFFF;
};
Implementation of LD BC, d16
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Address
PC (Program Counter)
C

57. //LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
$parentObj->registerC =
$parentObj->memoryReader[$parentObj->programCounter]($parentObj, $parentObj->programCounter);
$parentObj->registerB =
$parentObj->memoryRead(($parentObj->programCounter + 1) & 0xFFFF);
$parentObj->programCounter = ($parentObj->programCounter + 2) & 0xFFFF;
};
Implementation of LD BC, d16
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Address
PC (Program Counter)
B

58. //LD BC, nn
//#0x01:
$this->functionsArray[] = function ($parentObj) {
$parentObj->registerC =
$parentObj->memoryReader[$parentObj->programCounter]($parentObj, $parentObj->programCounter);
$parentObj->registerB =
$parentObj->memoryRead(($parentObj->programCounter + 1) & 0xFFFF);
$parentObj->programCounter = ($parentObj->programCounter + 2) & 0xFFFF;
};
Implementation of LD BC, d16
0x0000 0x0001 0x0002 0x003 0x004 0x005 0x0301
0x01 0x01 0x03 0x3e 0x99 0x02 0x99
LD BC, d16 0x0301 LD A, d8 0x99 LD (BC), A
Data
Instruction
Address
PC (Program Counter)

59. Implementation of JP a16
x3
cx
JP a16
3 16
- - - -

60. Implementation of JP a16
x3
cx
JP a16
3 16
- - - -
Jump to address a16

61. Implementation of JP a16
x3
cx
JP a16
3 16
- - - -
Jump to address a16
0x0000 0x0001 0x0002
0xc3 0x29 0x03
JP a16 0x0329
Data
Instruction
Address

62. Implementation of JP a16
x3
cx
JP a16
3 16
- - - -
Jump to address a16
0x0000 0x0001 0x0002
0xc3 0x29 0x03
JP a16 0x0329
Data
Instruction
Address
Jump to address 0x0329

63. Implementation of JP a16
x3
cx
JP a16
3 16
- - - -
Jump to address a16
//JP nn
//#0xC3:
$this->functionsArray[] = function ($parentObj) {
$parentObj->programCounter =
($parentObj->memoryRead(($parentObj->programCounter + 1) & 0xFFFF) << 8) +
$parentObj->memoryReader[$parentObj->programCounter]($parentObj, $parentObj->programCounter);
};
0x0000 0x0001 0x0002
0xc3 0x29 0x03
JP a16 0x0329
Data
Instruction
Address
Jump to address 0x0329

64. Run loop
public function executeIteration()
{
$op = 0;
while ($this->stopEmulator == 0) {
$op = $this->memoryRead($this->programCounter);
$this->programCounter = ($this->programCounter + 1) & 0xFFFF;
$this->CPUTicks = $this->TICKTable[$op];
$this->OPCODE[$op]($this);
$this->updateCore();
}
}

65. Not difficult
Simple, Easy

66. Let’s read
php-terminal-gameboy-emulator

67. Thanks
@tomzoh
WE ARE HIRING
Drupal / Mobile App Engineer
Digital Circus, Inc. Tokyo, Japan
@tomzoh

68. Links
• https://en.wikipedia.org/wiki/Game_Boy
• http://www.pastraiser.com/cpu/gameboy/gameboy_opcodes.html
• http://gbdev.gg8.se/wiki/articles/The_Cartridge_Header
• http://gameboy.mongenel.com/dmg/asmmemmap.html

69. More FPS?
PHP5.5.30 OSX Native
FPS: 4
PHP7.0.1 VirtualBox
FPS: 14

70. Duration in cycles table
<?php
namespace GameBoy;
class TickTables
{
public static $primary = [
//Number of machine cycles for each instruction:
/* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F*/
1, 3, 2, 2, 1, 1, 2, 1, 5, 2, 2, 2, 1, 1, 2, 1, //0
1, 3, 2, 2, 1, 1, 2, 1, 3, 2, 2, 2, 1, 1, 2, 1, //1
2, 3, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, //2
2, 3, 2, 2, 3, 3, 3, 1, 2, 2, 2, 2, 1, 1, 2, 1, //3

71. Duration in cycles table
<?php
namespace GameBoy;
class TickTables
{
public static $primary = [
//Number of machine cycles for each instruction:
/* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F*/
1, 3, 2, 2, 1, 1, 2, 1, 5, 2, 2, 2, 1, 1, 2, 1, //0
1, 3, 2, 2, 1, 1, 2, 1, 3, 2, 2, 2, 1, 1, 2, 1, //1
2, 3, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, //2
2, 3, 2, 2, 3, 3, 3, 1, 2, 2, 2, 2, 1, 1, 2, 1, //3
1 machine cycle = 4 clocks

72. Duration in cycles table
<?php
namespace GameBoy;
class TickTables
{
public static $primary = [
//Number of machine cycles for each instruction:
/* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F*/
1, 3, 2, 2, 1, 1, 2, 1, 5, 2, 2, 2, 1, 1, 2, 1, //0
1, 3, 2, 2, 1, 1, 2, 1, 3, 2, 2, 2, 1, 1, 2, 1, //1
2, 3, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, //2
2, 3, 2, 2, 3, 3, 3, 1, 2, 2, 2, 2, 1, 1, 2, 1, //3
1 machine cycle = 4 clocks
x4
cx
CALL NZ,a16
3 24/12
- - - -

73. Duration in cycles table
<?php
namespace GameBoy;
class TickTables
{
public static $primary = [
//Number of machine cycles for each instruction:
/* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F*/
1, 3, 2, 2, 1, 1, 2, 1, 5, 2, 2, 2, 1, 1, 2, 1, //0
1, 3, 2, 2, 1, 1, 2, 1, 3, 2, 2, 2, 1, 1, 2, 1, //1
2, 3, 2, 2, 1, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, //2
2, 3, 2, 2, 3, 3, 3, 1, 2, 2, 2, 2, 1, 1, 2, 1, //3
1 machine cycle = 4 clocks
x4
cx
CALL NZ,a16
3 24/12
- - - -Call address a16 if A resistor
is zero. It takes 24 clocks.

74. 5月 チケット販売開始 /トーク募集開始
6月上旬 トーク募集〆切
6月下旬 タイムテーブル決定
iOS Developers Conference Japan 2016
2016.08.20 https://iosdc.jp
スポンサー企業さま、大絶賛募集中