PACT assembly musings

gistfile1.txt

# line comments

# must start with a pact directive giving type and version
.pact pbc 0

# enable compiler options
# 2 reasons:
#  1) to allow an extremely basic version to be turned into a C implementation
#  2) to allow experimentation.  Most common options probably on by default in
#     higher versions
.options alias, var

# Possible options:
#  autoend:  end a segment when a new one starts
#  debug:    add debug segment information based on filename
#  annotate: add file/line annotations

# var may imply alias 

.constants num
0 3.14
1 0
2 1
3 "example.pas"
.end
.alias pi   = nc0 # these are file scope
.alias zero = nc1
.alias one  = nc2

.constants string
# encoding, string
# " strings have \-encoding
# ' strings only have \' and \\
# hex, base64 strings?
0 utf8 "Hello, World"
1 ascii "main"
2 ascii "line"
.end
.alias hello = sc0
.alias line  = sc2

.constants pmc
# type, then type dependent serialization
# For sub: label, name (must be SC#), options (main, tag, subid)
0 Sub main sc1, main
.end

# Print "Hello, World" three times
.sub main # sub "names" are actually labels, referred to in .constants pmc section
    .debug sc3 # set the file name for the debug segment
    .annotate line, 1 # add an annotation: type, value (type must be sc#, value any constant)
    .var i = n # becomes (highest num register used + 1), in this case n0
               # also scoped to sub
    set i, pi
loop:
    lt i, zero, done
    say hello
    sub i, one
    goto loop
done:
    end
.end

# aliases, vars, and labels all have same namespace.
# must match [_\w][_\w\d]*
# can't match [insp]c?\d+ (would conflict with register/constants)

# .subs have unique namespace (only used for Sub constants)

# disassembler will output _PC labels for every opcode (_0, _4)
# makes it easy to output jumps

# How do we want to handle integer constants?
# .alias const = 42
# .const const = 42

# This code isn't really PASM, but the highlighting works well.
# vim: expandtab shiftwidth=4 ft=pasm: