How to Implement a CPU Emulator in Scheme

How to Implement a CPU Emulator in Scheme

Representa9ve of MCPC

Kazuhiro Hishinuma

MCPC: a Compe99ve Programming Circle 1

hBp://mcpc.arnip.org/ #csmeiji

The Trigger to Implement a CPU Emulator






( ◠‿◠ )☛ Make It Yourself


▂▅▇█▓▒░('ω')░▒▓█▇▅▂ ▂▅▇█▓▒░('ω')░▒▓█▇▅▂ ▂▅▇█▓▒░('ω')░▒▓█▇▅▂


The Reason to Implement in Scheme


In Scheme, You can …

Get Current Con9nua9on And

Return Mul9ple Values


Con9nua9on...?

/* Pseudo-‐Code */ func9on f ( x ) { res = x + 1; return ( res ); };


Con9nua9on := A Func9on-‐Like Object To Return Value!!!

What’s the Difference Between Func9on And Con9nua9on??


( ◠‿◠ )☛In Func9on


PROGRAM FUNCTION

CALL

RETURN

( ◠‿◠ )☛In Con9nua9on


PROGRAM CONTINU-‐ ATION

CALL

( ◠‿◠ )☛ A Con9nua9on is Like A Func9on, But It Won’t Return.


o。(˘⊖˘ ) A Con9nua9on is Like A Func9on…?


┗(☋｀ )┓三 return ( a, b, c );


f ( x ) returns y


f ( x )

x

y

f ( x ) returns ( a, b, c )


f ( x )

x a

b

c

ヾ(*＞ヮ＜)ﾉ” A Func9on Returns Mul9ple Values!!


Mul9ple Values Func9on


f ( x )

x a

b

c

Composing Func9ons


f ( x ) g ( a, b, c )

x

d

e

Composing Func9ons…?


fetch generator

3

2

This is a Hardware Diagram!!


clk_gen

counter

MUX 0

decoder

dec7seg

dec7seg

＿人人人人人人人人＿＞　Scheme is a HDL!!　＜‾^Y^Y^Y^Y^Y^Y^Y^Y^‾


The Way to Implement a CPU Emulator


( ◠‿◠ )☛Read it!


( ◠‿◠ )☛980 yen (tax in)


日経吔听吟叽叿叹

咇咅咅咎年咅咇月号

( ◠‿◠ )☛Implement It!!


<machine>

gr mem

pc

fr fetch

run

(ฅ`･ω･´)っ= There is One Problem.


State Transi9on on Hardware is …

DESTRUCTIVE!!


Destruc9ve State Transi9on

/* Pseudo-‐Code, Given s: Current State */ S1: /* Procedure of State S1 */

s = /* S1-‐>S2 */( s ); goto S2;

S2: /* Procedure of State S2 */

/* … */


Pure State Transi9on

/* Pseudo-‐Code, Given s: Current State */ func9on S1 ( s ) { /* Procedure of State S1 */ return S2 ( /* S1-‐>S2 */( s ) ); } func9on S2 ( s ) { /* Procedure of State S2 ...


Tail Call

p (`･ω･´q) It’s Solved.


The Result of Implement in Scheme


( ◠‿◠ )☛Demonstra9on


hBps://gist.github.com/kazh98/5117299　解説: hBp://qiita.com/items/b667dc18e769c4bf857e hBps://gist.github.com/kazh98/5213280　解説: このスライド

Conclusion

•  Scheme is a Hardware Descrip9on Language. •  State Transi9on can be Expressed as Tail Call. •  To Implement CPU Emulator is interes9ng.

Let us Be a Schemer!!


Thanks for YOUR listening!


hBp://mcpc.arnip.org/

Technology

How to Implement a CPU Emulator in Scheme