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# Integer arithmetic using postfix notation
#
# Limitations:
# Division not implemented yet.
#
# To build:
# $ ./translate rpn.mu
#
# Example session:
# $ qemu-system-i386 code.img
# > 4
# 4
# > 5 3 -
# 2
#
# Error handling is non-existent. This is just a prototype.
fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
var in-storage: (stream byte 0x80)
var in/esi: (addr stream byte) <- address in-storage
var y/ecx: int <- copy 0
var space/edx: grapheme <- copy 0x20
# read-eval-print loop
{
# print prompt
var x/eax: int <- draw-text-rightward screen, "> ", 0/x, 0x80/xmax, y, 3/fg/cyan, 0/bg
set-cursor-position screen, x, y
# read line from keyboard
clear-stream in
{
draw-cursor screen, space
var key/eax: byte <- read-key keyboard
compare key, 0xa/newline
break-if-=
compare key, 0
loop-if-=
var key2/eax: int <- copy key
append-byte in, key2
var g/eax: grapheme <- copy key2
draw-grapheme-at-cursor screen, g, 0xf/fg, 0/bg
move-cursor-right 0
loop
}
# clear cursor
draw-grapheme-at-cursor screen, space, 3/fg/never-used, 0/bg
# parse and eval
var out/eax: int <- simplify in
# print
y <- increment
out, y <- draw-int32-decimal-wrapping-right-then-down screen, out, 0/xmin, y, 0x80/xmax, 0x30/ymax, 0/x, y, 7/fg, 0/bg
# newline
y <- increment
#
loop
}
}
type int-stack {
data: (handle array int)
top: int
}
fn simplify in: (addr stream byte) -> _/eax: int {
var word-storage: slice
var word/ecx: (addr slice) <- address word-storage
var stack-storage: int-stack
var stack/esi: (addr int-stack) <- address stack-storage
initialize-int-stack stack, 0x10
$simplify:word-loop: {
next-word in, word
var done?/eax: boolean <- slice-empty? word
compare done?, 0
break-if-!=
# if word is an operator, perform it
{
var is-add?/eax: boolean <- slice-equal? word, "+"
compare is-add?, 0
break-if-=
var _b/eax: int <- pop-int-stack stack
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack stack
a <- add b
push-int-stack stack, a
loop $simplify:word-loop
}
{
var is-sub?/eax: boolean <- slice-equal? word, "-"
compare is-sub?, 0
break-if-=
var _b/eax: int <- pop-int-stack stack
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack stack
a <- subtract b
push-int-stack stack, a
loop $simplify:word-loop
}
{
var is-mul?/eax: boolean <- slice-equal? word, "*"
compare is-mul?, 0
break-if-=
var _b/eax: int <- pop-int-stack stack
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack stack
a <- multiply b
push-int-stack stack, a
loop $simplify:word-loop
}
# otherwise it's an int
var n/eax: int <- parse-decimal-int-from-slice word
push-int-stack stack, n
loop
}
var result/eax: int <- pop-int-stack stack
return result
}
fn initialize-int-stack _self: (addr int-stack), n: int {
var self/esi: (addr int-stack) <- copy _self
var d/edi: (addr handle array int) <- get self, data
populate d, n
var top/eax: (addr int) <- get self, top
copy-to *top, 0
}
fn push-int-stack _self: (addr int-stack), _val: int {
var self/esi: (addr int-stack) <- copy _self
var top-addr/ecx: (addr int) <- get self, top
var data-ah/edx: (addr handle array int) <- get self, data
var data/eax: (addr array int) <- lookup *data-ah
var top/edx: int <- copy *top-addr
var dest-addr/edx: (addr int) <- index data, top
var val/eax: int <- copy _val
copy-to *dest-addr, val
add-to *top-addr, 1
}
fn pop-int-stack _self: (addr int-stack) -> _/eax: int {
var self/esi: (addr int-stack) <- copy _self
var top-addr/ecx: (addr int) <- get self, top
{
compare *top-addr, 0
break-if->
return 0
}
subtract-from *top-addr, 1
var data-ah/edx: (addr handle array int) <- get self, data
var data/eax: (addr array int) <- lookup *data-ah
var top/edx: int <- copy *top-addr
var result-addr/eax: (addr int) <- index data, top
var val/eax: int <- copy *result-addr
return val
}
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