start 04b compiler

04b/in04b

@@ -0,0 +1,96 @@
+; types: char, short, int, long, *type
+; declaration:
+;     global <type> <name>
+;     local  <type> <name>
+;     :<label>
+; statement:
+;     <declaration>
+;     if <term> <==/</>/>=/<=/!=> <term> goto <label>   NOTE: this uses signed comparisons
+;     goto <label>
+;     <lvalue> = <rvalue>
+;     <lvalue> += <rvalue>
+;     <lvalue> -= <rvalue>
+;     <function>(<term>, <term>, ...)
+;     syscall(<term>, <term>, ...)
+;     return <rvalue>
+;     byte <number>
+; term:
+;     <var>
+;     <number>
+; number:
+;     'c
+;     12345
+;     0xabc
+; lvalue:
+;     <var>
+;     *<var>
+;     <var>[<term>]
+; rvalue:
+;     `<string>`
+;     <var>
+;     &<var>
+;     *<var>
+;     <var>[<term>]
+;     ~<var>
+;     <function>(<term>, <term>, ...)
+;     syscall(<term>, <term>, ...)
+;     <term> + <term>
+;     <term> - <term>
+;    NOTE: *, /, % are signed (imul and idiv)
+;     <term> * <term>
+;     <term> / <term>
+;     <term> % <term>
+;     <term> & <term>
+;     <term> | <term>
+;     <term> ^ <term>
+;     <term> < <term>  (left shift)
+;     <term> > <term>  (unsigned right shift)
+
+main() ; hello
+
+global char x
+global short y ;123
+global long z
+
+function strlen(*char s)
+	local long len
+	local char c
+	len = 0
+	:strlen.loop
+	c = s[len]
+	if c == 0 goto strlen.loop_end
+	len += 1
+	goto strlen.loop
+	:strlen.loop_end
+	return len
+
+function putc(char c)
+	local char *p
+	p = &c
+	syscall(1, 1, p, 1, 0, 0, 0, 0)
+	return
+	
+function puts(*char s)
+	local long len
+	len = strlen(s)
+	syscall(1, 1, s, len, 0, 0, 0, 0)
+	return
+
+function main()
+	local *char hello
+	hello = `Hello, world!
+`
+	puts(hello)
+	syscall(0x3c, 0, 0, 0, 0, 0, 0, 0)
+
+function f(*long x, *long y)
+	local long v
+	local *long p
+	v = *x
+	p = *y
+	*p = v
+	if v == 0 goto something
+	p[1] = v + 1
+	return p[2]
+	:something
+	return p[1]