# streams: data structure for operating on arrays in a stateful manner
#
# A stream looks like this:
#   write: int  # index at which writes go
#   read: int  # index that we've read until
#   data: (array byte)  # prefixed by size as usual
#
# some primitives for operating on streams:
#   - clear-stream (clears everything but the data size)
#   - rewind-stream (resets read pointer)

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

clear-stream:  # f: (addr stream byte)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    # eax = f
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
    # var count/ecx: int = f->size
    8b/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(eax+8) to ecx
    # var max/ecx: (addr byte) = &f->data[f->size]
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   0xc/disp8       .                 # copy eax+ecx+12 to ecx
    # f->write = 0
    c7          0/subop/copy        0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm32           # copy to *eax
    # f->read = 0
    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         0/imm32           # copy to *(eax+4)
    # - clear all stream data
    # - this isn't strictly necessary, and it can slow things down *a lot*, but better safe than sorry.
    # var curr/eax: (addr byte) = f->data
    81          0/subop/add         3/mod/direct    0/rm32/eax    .           .             .           .           .               0xc/imm32         # add to eax
$clear-stream:loop:
    # if (curr >= max) break
    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # compare eax with ecx
    73/jump-if-addr>=  $clear-stream:end/disp8
    # *curr = 0
    c6          0/subop/copy-byte   0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm8            # copy byte to *eax
    # ++curr
    40/increment-eax
    eb/jump  $clear-stream:loop/disp8
$clear-stream:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

rewind-stream:  # f: (addr stream byte)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    # eax = f
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
    # f->read = 0
    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         0/imm32           # copy to *(eax+4)
$rewind-stream:end:
    # . restore registers
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# . . vim:nowrap:textwidth=0

fn initialize-word _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  allocate data-ah
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  initialize-gap-buffer data
  # TODO: sometimes initialize box-data rather than scalar-data
}

## some helpers for creating words. mostly for tests

fn initialize-word-with _self: (addr word), s: (addr array byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  allocate data-ah
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  initialize-gap-buffer-with data, s
}

fn allocate-word-with _out: (addr handle word), s: (addr array byte) {
  var out/eax: (addr handle word) <- copy _out
  allocate out
  var out-addr/eax: (addr word) <- lookup *out
  initialize-word-with out-addr, s
}

# just for tests for now
# TODO: handle existing next
# one implication of handles: append must take a handle
fn append-word-with self-h: (handle word), s: (addr array byte) {
  var self/eax: (addr word) <- lookup self-h
  var next-ah/eax: (addr handle word) <- get self, next
  allocate-word-with next-ah, s
  var next/eax: (addr word) <- lookup *next-ah
  var prev-ah/eax: (addr handle word) <- get next, prev
  copy-handle self-h, prev-ah
}

# just for tests for now
# TODO: handle existing prev
fn prepend-word-with self-h: (handle word), s: (addr array byte) {
  var self/eax: (addr word) <- lookup self-h
  var prev-ah/eax: (addr handle word) <- get self, prev
  allocate-word-with prev-ah, s
  var prev/eax: (addr word) <- lookup *prev-ah
  var next-ah/eax: (addr handle word) <- get prev, next
  copy-handle self-h, next-ah
}

## real primitives

fn move-word-contents _src-ah: (addr handle word), _dest-ah: (addr handle word) {
  var dest-ah/eax: (addr handle word) <- copy _dest-ah
  var _dest/eax: (addr word) <- lookup *dest-ah
  var dest/edi: (addr word) <- copy _dest
  var src-ah/eax: (addr handle word) <- copy _src-ah
  var _src/eax: (addr word) <- lookup *src-ah
  var src/esi: (addr word) <- copy _src
  cursor-to-start src
  var src-data-ah/eax: (addr handle gap-buffer) <- get src, scalar-data
  var src-data/eax: (addr gap-buffer) <- lookup *src-data-ah
  var src-stack/ecx: (addr grapheme-stack) <- get src-data, right
  {
    var done?/eax: boolean <- grapheme-stack-empty? src-stack
    compare done?, 0  # false
    break-if-!=
    var g/eax: grapheme <- pop-grapheme-stack src-stack
#?     print-grapheme 0, g
#?     print-string 0, "\n"
    add-grapheme-to-word dest, g
    loop
  }
}

fn copy-word-contents-before-cursor _src-ah: (addr handle word), _dest-ah: (addr handle word) {
  var dest-ah/eax: (addr handle word) <- copy _dest-ah
  var _dest/eax: (addr word) <- lookup *dest-ah
  var dest/edi: (addr word) <- copy _dest
  var src-ah/eax: (addr handle word) <- copy _src-ah
  var src/eax: (addr word) <- lookup *src-ah
  var src-data-ah/eax: (addr handle gap-buffer) <- get src, scalar-data
  var src-data/eax: (addr gap-buffer) <- lookup *src-data-ah
  var src-stack/ecx: (addr grapheme-stack) <- get src-data, left
  var src-stack-data-ah/eax: (addr handle array grapheme) <- get src-stack, data
  var _src-stack-data/eax: (addr array grapheme) <- lookup *src-stack-data-ah
  var src-stack-data/edx: (addr array grapheme) <- copy _src-stack-data
  var top-addr/ecx: (addr int) <- get src-stack, top
  var i/eax: int <- copy 0
  {
    compare i, *top-addr
    break-if->=
    var g/edx: (addr grapheme) <- index src-stack-data, i
    add-grapheme-to-word dest, *g
    i <- increment
    loop
  }
}

fn word-equal? _self: (addr word), s: (addr array byte) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-buffer-equal? data, s
}

fn word-length _self: (addr word) -> result/eax: int {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-buffer-length data
}

fn first-word _in: (addr handle word), out: (addr handle word) {
  var curr-ah/esi: (addr handle word) <- copy _in
  var curr/eax: (addr word) <- lookup *curr-ah
  var prev/edi: (addr handle word) <- copy 0
  {
    prev <- get curr, prev
    var curr/eax: (addr word) <- lookup *prev
    compare curr, 0
    break-if-=
    copy-object prev, curr-ah
    loop
  }
  copy-object curr-ah, out
}

fn final-word _in: (addr handle word), out: (addr handle word) {
  var curr-h: (handle word)
  var curr-ah/esi: (addr handle word) <- address curr-h
  copy-object _in, curr-ah
  var curr/eax: (addr word) <- copy 0
  var next/edi: (addr handle word) <- copy 0
  {
    curr <- lookup *curr-ah
    next <- get curr, next
    curr <- lookup *next
    compare curr, 0
    break-if-=
    copy-object next, curr-ah
    loop
  }
  copy-object curr-ah, out
}

fn first-grapheme _self: (addr word) -> result/eax: grapheme {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- first-grapheme-in-gap-buffer data
}

fn add-grapheme-to-word _self: (addr word), c: grapheme {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  add-grapheme-at-gap data, c
}

fn cursor-at-start? _self: (addr word) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-at-start? data
}

fn cursor-at-end? _self: (addr word) -> result/eax: boolean {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-at-end? data
}

fn cursor-left _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  var dummy/eax: grapheme <- gap-left data
}

fn cursor-right _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  var dummy/eax: grapheme <- gap-right data
}

fn cursor-to-start _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-to-start data
}

fn cursor-to-end _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-to-end data
}

fn cursor-index _self: (addr word) -> result/eax: int {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-index data
}

fn delete-before-cursor _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  delete-before-gap data
}

fn delete-next _self: (addr word) {
$delete-next:body: {
  var self/esi: (addr word) <- copy _self
  var next-ah/edi: (addr handle word) <- get self, next
  var next/eax: (addr word) <- lookup *next-ah
  compare next, 0
  break-if-= $delete-next:body
  var next-next-ah/ecx: (addr handle word) <- get next, next
  var self-ah/esi: (addr handle word) <- get next, prev
  copy-object next-next-ah, next-ah
  var new-next/eax: (addr word) <- lookup *next-next-ah
  compare new-next, 0
  break-if-= $delete-next:body
  var dest/eax: (addr handle word) <- get new-next, prev
  copy-object self-ah, dest
}
}

fn print-word screen: (addr screen), _self: (addr word) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  render-gap-buffer screen, data
}

fn print-words screen: (addr screen), _words-ah: (addr handle word) {
  var words-ah/eax: (addr handle word) <- copy _words-ah
  var words-a/eax: (addr word) <- lookup *words-ah
  compare words-a, 0
  break-if-=
  # print
  print-word screen, words-a
  print-string screen, " "
  # recurse
  var next-ah/eax: (addr handle word) <- get words-a, next
  print-words screen, next-ah
}

fn print-words-in-reverse screen: (addr screen), _words-ah: (addr handle word) {
  var words-ah/eax: (addr handle word) <- copy _words-ah
  var words-a/eax: (addr word) <- lookup *words-ah
  compare words-a, 0
  break-if-=
  # recurse
  var next-ah/ecx: (addr handle word) <- get words-a, next
  print-words screen, next-ah
  # print
  print-word screen, words-a
  print-string screen, " "
}

# Gotcha with some word operations: ensure dest-ah isn't in the middle of some
# existing chain of words. There are two pointers to patch, and you'll forget
# to do the other one.
fn copy-words _src-ah: (addr handle word), _dest-ah: (addr handle word) {
  var src-ah/eax: (addr handle word) <- copy _src-ah
  var src-a/eax: (addr word) <- lookup *src-ah
  compare src-a, 0
  break-if-=
  # copy
  var dest-ah/edi: (addr handle word) <- copy _dest-ah
  copy-word src-a, dest-ah
  # recurse
  var rest: (handle word)
  var rest-ah/ecx: (addr handle word) <- address rest
  var next-src-ah/esi: (addr handle word) <- get src-a, next
  copy-words next-src-ah, rest-ah
  chain-words dest-ah, rest-ah
}

fn copy-words-in-reverse _src-ah: (addr handle word), _dest-ah: (addr handle word) {
  var src-ah/eax: (addr handle word) <- copy _src-ah
  var _src-a/eax: (addr word) <- lookup *src-ah
  var src-a/esi: (addr word) <- copy _src-a
  compare src-a, 0
  break-if-=
  # recurse
  var next-src-ah/ecx: (addr handle word) <- get src-a, next
  var dest-ah/edi: (addr handle word) <- copy _dest-ah
  copy-words-in-reverse next-src-ah, dest-ah
  #
  copy-word-at-end src-a, dest-ah
}

fn copy-word-at-end src: (addr word), _dest-ah: (addr handle word) {
$copy-word-at-end:body: {
  var dest-ah/edi: (addr handle word) <- copy _dest-ah
  # if dest is null, copy and return
  var dest-a/eax: (addr word) <- lookup *dest-ah
  compare dest-a, 0
  {
    break-if-!=
    copy-word src, dest-ah
    break $copy-word-at-end:body
  }
  # copy current word
  var new: (handle word)
  var new-ah/ecx: (addr handle word) <- address new
  copy-word src, new-ah
  # append it at the end
  var curr-ah/edi: (addr handle word) <- copy dest-ah
  {
    var curr-a/eax: (addr word) <- lookup *curr-ah  # curr-a guaranteed not to be null
    var next-ah/ecx: (addr handle word) <- get curr-a, next
    var next-a/eax: (addr word) <- lookup *next-ah
    compare next-a, 0
    break-if-=
    curr-ah <- copy next-ah
    loop
  }
  chain-words curr-ah, new-ah
}
}

fn append-word-at-end-with _dest-ah: (addr handle word), s: (addr array byte) {
$append-word-at-end-with:body: {
  var dest-ah/edi: (addr handle word) <- copy _dest-ah
  # if dest is null, copy and return
  var dest-a/eax: (addr word) <- lookup *dest-ah
  compare dest-a, 0
  {
    break-if-!=
    allocate-word-with dest-ah, s
    break $append-word-at-end-with:body
  }
  # otherwise append at end
  var curr-ah/edi: (addr handle word) <- copy dest-ah
  {
    var curr-a/eax: (addr word) <- lookup *curr-ah  # curr-a guaranteed not to be null
    var next-ah/ecx: (addr handle word) <- get curr-a, next
    var next-a/eax: (addr word) <- lookup *next-ah
    compare next-a, 0
    break-if-=
    curr-ah <- copy next-ah
    loop
  }
  append-word-with *curr-ah, s
}
}

fn copy-word _src-a: (addr word), _dest-ah: (addr handle word) {
  var dest-ah/eax: (addr handle word) <- copy _dest-ah
  allocate dest-ah
  var _dest-a/eax: (addr word) <- lookup *dest-ah
  var dest-a/eax: (addr word) <- copy _dest-a
  initialize-word dest-a
  var dest/edi: (addr handle gap-buffer) <- get dest-a, scalar-data
  var src-a/eax: (addr word) <- copy _src-a
  var src/eax: (addr handle gap-buffer) <- get src-a, scalar-data
  copy-gap-buffer src, dest
}

# one implication of handles: append must take a handle
fn append-word _self-ah: (addr handle word) {
  var saved-self-storage: (handle word)
  var saved-self/eax: (addr handle word) <- address saved-self-storage
  copy-object _self-ah, saved-self
#?   {
#?     print-string 0, "self-ah is "
#?     var foo/eax: int <- copy _self-ah
#?     print-int32-hex 0, foo
#?     print-string 0, "\n"
#?   }
  var self-ah/esi: (addr handle word) <- copy _self-ah
  var _self/eax: (addr word) <- lookup *self-ah
  var self/ebx: (addr word) <- copy _self
#?   {
#?     print-string 0, "0: self is "
#?     var self-ah/eax: (addr handle word) <- copy _self-ah
#?     var self/eax: (addr word) <- lookup *self-ah
#?     var foo/eax: int <- copy self
#?     print-int32-hex 0, foo
#?     print-string 0, "\n"
#?   }
  # allocate new handle
  var new: (handle word)
  var new-ah/ecx: (addr handle word) <- address new
  allocate new-ah
  var new-addr/eax: (addr word) <- lookup new
  initialize-word new-addr
#?   {
#?     print-string 0, "new is "
#?     var foo/eax: int <- copy new-addr
#?     print-int32-hex 0, foo
#?     print-string 0, "\n"
#?   }
  # new->next = self->next
  var src/esi: (addr handle word) <- get self, next
#?   {
#?     print-string 0, "src is "
#?     var foo/eax: int <- copy src
#?     print-int32-hex 0, foo
#?     print-string 0, "\n"
#?   }
  var dest/edi: (addr handle word) <- get new-addr, next
  copy-object src, dest
  # new->next->prev = new
  {
    var next-addr/eax: (addr word) <- lookup *src
    compare next-addr, 0
    break-if-=
#?     {
#?       print-string 0, "next-addr is "
#?       var foo/eax: int <- copy next-addr
#?       print-int32-hex 0, foo
#?       print-string 0, "\n"
#?     }
    dest <- get next-addr, prev
#? #?     {
#? #?       print-string 0, "self-ah is "
#? #?       var foo/eax: int <- copy _self-ah
#? #?       print-int32-hex 0, foo
#? #?       print-string 0, "\n"
#? #?       print-string 0, "2: self is "
#? #?       var self-ah/eax: (addr handle word) <- copy _self-ah
#? #?       var self/eax: (addr word) <- lookup *self-ah
#? #?       var foo/eax: int <- copy self
#? #?       print-int32-hex 0, foo
#? #?       print-string 0, "\n"
#? #?     }
#?     {
#?       print-string 0, "copying new to "
#?       var foo/eax: int <- copy dest
#?       print-int32-hex 0, foo
#?       print-string 0, "\n"
#?     }
    copy-object new-ah, dest
#?     {
#?       print-string 0, "4: self is "
#?       var self-ah/eax: (addr handle word) <- copy _self-ah
#?       var self/eax: (addr word) <- lookup *self-ah
#?       var foo/eax: int <- copy self
#?       print-int32-hex 0, foo
#?       print-string 0, "\n"
#?     }
  }
  # new->prev = saved-self
  dest <- get new-addr, prev
#?   {
#?     print-string 0, "copying "
#?     var self-ah/esi: (addr handle word) <- copy _self-ah
#?     var self/eax: (addr word) <- lookup *self-ah
#?     var foo/eax: int <- copy self
#?     print-int32-hex 0, foo
#?     print-string 0, " to "
#?     foo <- copy dest
#?     print-int32-hex 0, foo
#?     print-string 0, "\n"
#?   }
  var saved-self-ah/eax: (addr handle word) <- address saved-self-storage
  copy-object saved-self-ah, dest
  # self->next = new
  dest <- get self, next
  copy-object new-ah, dest
}

fn chain-words _self-ah: (addr handle word), _next: (addr handle word) {
  var self-ah/esi: (addr handle word) <- copy _self-ah
  var _self/eax: (addr word) <- lookup *self-ah
  var self/ecx: (addr word) <- copy _self
  var dest/edx: (addr handle word) <- get self, next
  var next-ah/edi: (addr handle word) <- copy _next
  copy-object next-ah, dest
  var next/eax: (addr word) <- lookup *next-ah
  compare next, 0
  break-if-=
  dest <- get next, prev
  copy-object self-ah, dest
}

fn emit-word _self: (addr word), out: (addr stream byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  emit-gap-buffer data, out
}

fn word-to-string _self: (addr word), out: (addr handle array byte) {
  var self/esi: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  gap-buffer-to-string data, out
}

fn word-is-decimal-integer? _self: (addr word) -> result/eax: boolean {
  var self/eax: (addr word) <- copy _self
  var data-ah/eax: (addr handle gap-buffer) <- get self, scalar-data
  var data/eax: (addr gap-buffer) <- lookup *data-ah
  result <- gap-buffer-is-decimal-integer? data
}

# ABSOLUTELY GHASTLY
fn word-exists? _haystack-ah: (addr handle word), _needle: (addr word) -> result/ebx: boolean {
  var needle-name-storage: (handle addr byte)
  var needle-name-ah/eax: (addr handle array byte) <- address needle-name-storage
  word-to-string _needle, needle-name-ah  # profligate leak
  var _needle-name/eax: (addr array byte) <- lookup *needle-name-ah
  var needle-name/edi: (addr array byte) <- copy _needle-name
  # base case
  result <- copy 0   # false
  var haystack-ah/esi: (addr handle word) <- copy _haystack-ah
  var curr/eax: (addr word) <- lookup *haystack-ah
  compare curr, 0
  break-if-=
  # check curr
  var curr-name-storage: (handle addr byte)
  var curr-name-ah/ecx: (addr handle array byte) <- address curr-name-storage
  word-to-string curr, curr-name-ah  # profligate leak
  var curr-name/eax: (addr array byte) <- lookup *curr-name-ah
  var found?/eax: boolean <- string-equal? needle-name, curr-name
  result <- copy found?
  compare result, 0
  break-if-!=
  # recurse
  var curr/eax: (addr word) <- lookup *haystack-ah
  var next-haystack-ah/eax: (addr handle word) <- get curr, next
  result <- word-exists? next-haystack-ah, _needle
}