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mruby de Hello World!

2019-11-03

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The Presentation for RubyKaigiToyama01 by hasumikin

Text

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mruby de Hello World!
HASUMI Hitoshi @hasumikin
Monstar Lab, Shimane office
富山Ruby会議01
2019-11-03

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Today is

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Today is
My birthday 🎂

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me
HASUMI Hitoshi
@hasumikin
Microcontroller
detective
RubyKaigi 2018, 2019
RubyWorld 2018
KRKRB 2019 (Poland)
RubyConf 2019 (the US)

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RubyWorld Conference 2019
Nov. 7-8, 2019 / Matz江, the Holy City of Ruby + 🍶

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RubyWorld Conference 2019
🍶熱燗 sponsored
by Monstar Lab

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Monstar Lab

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Monstar Lab
We don't have Toyama office, though

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Monstar Lab
@noboru_i

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Monstar Lab
石倉神

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Monstar Lab
いわゆるゴッド

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Monstar Lab
この人です

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Monstar Lab
WE ARE HIRING!

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Monstar Lab
採用してます

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mruby de Hello World!
How to code

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mruby de Hello World!
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puts "Hello World!"
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VM code
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RITE0006.x...bMA
TZ0000IREP...D00
02...`..........
..O......7.g....
...Hello World!.
.....puts.END...
..

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CRuby, mruby and mruby/c

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CRuby(2.6.4) + Ruby code
puts "Hello World!"
rss = `ps -o rss= -p #{Process.pid}`.to_f / 1024
vsz = `ps -o vsz= -p #{Process.pid}`.to_f / 1024
puts "RSS: #{rss} MB"
puts "VSZ: #{vsz} MB"
#
#
#
#
$ ruby hello.rb
Hello World!
RSS: 13.63671875 MB
VSZ: 78.6328125 MB

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mruby(2.0.1) + Ruby code
#include <mruby.h>
#include <mruby/compile.h> // compile at runtime
int main(void) {
mrb_state *mrb = mrb_open();
char code[] = "puts 'Hello World!'";
mrb_load_string(mrb, code);
mrb_close(mrb);
return 0;
}
// $ valgrind ./hello_ruby
// (...)
// Hello World!
// ==18802==
// ==18802== HEAP SUMMARY:
// ==18802==
in use at exit: 0 bytes in 0 blocks
// ==18802== total heap usage: 3,067 allocs, 3,067 frees,
//
379,851 bytes allocated

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mruby(2.0.1) + VM code
#include <mruby.h>
#include <mruby/irep.h>
#include "hello.c"
// compiled by mrbc
int main(void) {
mrb_state *mrb = mrb_open();
mrb_load_irep(mrb, hello);
mrb_close(mrb);
return 0;
}
// $ valgrind ./hello_vm
// (...)
// Hello World!
// ==18858==
// ==18858== HEAP SUMMARY:
// ==18858==
in use at exit: 0 bytes in 0 blocks
// ==18858== total heap usage: 3,057 allocs, 3,057 frees,
//
329,083 bytes allocated

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mruby/c(2.0) + VM code
#include "mrubyc/src/mrubyc.h"
#include "hello.c"
#define MEMORY_SIZE (1024 * 12) // RAM:12KB
static uint8_t my_memory_pool[MEMORY_SIZE];
int main(void) {
mrbc_init(my_memory_pool, MEMORY_SIZE);
mrbc_create_task(hello, 0);
mrbc_run();
return 0;
}

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Hello memory usage
ROM
RAM
ROM
/ RAM
CRuby + mruby + mruby + mruby/c
Ruby
Ruby VM code + VM
code
code
code
18MB(*) 3561KB 2736KB
148KB
13MB
370KB
321KB
12KB
1.3
9.6
8.5
12.3
(*)...binary size of `bin/ruby` itself

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CRuby, mruby and mruby/c

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mruby compiler
How to code?

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Steps of coding a compiler
Tokenize (Scan, Lexical analyze)
Parse
Generate Code
Not detailed enough 😵

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Steps of coding a compiler
Tokenize (Scan, Lexical analyze)
Find keywords
Classify tokens
Parse
Make syntax tree
Make symbol table
Make literal pool
Count local variables and registers
Make each scopes (文字数

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Steps of coding a compiler
Tokenize (Scan, Lexical analyze)
Parse
Generate Code
Just outlines for today

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mruby compiler written in CRuby
github.com/hasumikin/mmrbc.gem

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mruby compiler written in CRuby
github.com/hasumikin/mmrbc.gem
for only `puts "Hello World!"` 😂
`[identifier] "[string literal]"`

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mruby compiler written in CRuby
github.com/hasumikin/mmrbc.gem
for only `puts "Hello World!"` 😂
`[identifier] "[string literal]"`
but no cheat 😤

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Tokenizer
FLEX is a tokenizer generator
You can write tokenizer from scratch w/o FLEX
CRuby, mruby and mmrbc.gem, too
puts("Hello World!")
....................
p
pu
put
puts
puts( # look ahead
puts
# detemine a token

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Tokenizer of Ruby
It has state
$ irb
irb(main):001:0> [1, 2, 3].each do |n|
irb(main):002:1*
`do` keyword sets tokenizer_state as EXPR_BEG
irb can delay parsing until it becomes
EXPR_END with `end` keyword

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Parser and Parser generator
Parser
Syntactic analysis of token list
Parser generator
Generates C code of parser by syntactic definition
(and "reduction" code)
Parse algorithms
LL(n), LR(n), etc.

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Parse algorithm - LL(1)/LR(1)
LL(k) = Left to right, Leftmost derivation
You can write LL parser from scratch
LR(k) = Left to right, Rightmost derivation
You can hardly write LR parser from scratch
You should use parser generator
LALR(k) is a variation of LR
(k) = length of lookahead symbols

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Parser generator
YACC/BISON

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YACC/BISON
Most popular parser genarator
Used in CRuby, mruby, bash, Blawn, etc.
BISON is a GNU version of YACC
Thread safe (Reentrant)
Genarates LALR(1) parser

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However

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However
I don't use YACC/BISON

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So?

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So?
LEMON, instead

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LEMON?
Parser generator of SQLite
A part of SQLite project
Generates LALR(1) parser code
as well as YACC/BISON does
Doesn't use global variable to pass information
between parser and tokenizer
YACC/BISON does
Tokenizer calls parser in LEMON
Parser calls tokenizer in YACC/BISON

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Parser calls tokenizer in YACC/
BISON
int yyparse(parser_state *p) {
...
yynewstate:
...
yychar = yylex (&yylval, p); // calls tokenizer
...
goto yynewstate;
...
}

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Tokenizer calls parser in LEMON
void Tokenize(char *code) {
...
while (token == get_token(code)) {
...
Parse(parser, token, value); // calls parser
...
}
Parse(parser, 0, NULL);
}

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Parsing "Hello World!" in YACC
# an excerpt from mruby/mrbgems/mruby-compiler/core/parse.y
primary
: literal
| string
(...)
;
literal
: numeric
(...)
;
string
: string_fragment;
| string string_fragment
{ $$ = concat_string(p, $1, $2); }
;
string_fragment : tSTRING_BEG string_rep tSTRING
{ $$ = new_dstr(p, push($2, $3)); };
string_rep
: string_interp
| string_rep string_interp
{ $$ = append($1, $2); };
string_interp : tSTRING_MID
{ $$ = list1($1); };

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Parsing "Hello World!" in LEMON
# an excerpt from mmrbc.gem/ext/mmrbc/parse.y
primary
::= literal.
primary
::= string.
literal
::= numeric.
string
::= string_fragment.
string_fragment(A) ::= STRING_BEG string_rep(C) STRING.
{ A = new_dstr(p, list3(atom(ATOM_string_add),
list1(atom(ATOM_string_content)), C)); }
string_rep
::= string_interp.
string_rep(A)
::= string_rep(B) string_interp(C).
{ A = append(B, C); }
string_interp(A)
::= STRING_MID(B).
{ A = list2(atom(ATOM_at_tstring_content),
literal(B)); }

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DEMO?

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Future work

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Future work ->{mmrbc + mruby/c}
More syntax than `puts "Hello World!"`
Rewrite mmrbc.gem into C
And embed it with mruby/c in one-chip
microcontroller which has less than 512KB ROM
and 128KB RAM

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Future work ->{mmrbc + mruby/c}

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Future work ->{mmrbc + mruby/c}

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Future work ->{mmrbc + mruby/c}
"LEMON would generate smaller binary than YACC."

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Future work ->{mmrbc + mruby/c}
Possibly and hopefully,
I will see you on
RubyKaigi 2020 at Matsumoto

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Thank you!

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