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MIT/X Consortium License

(C)opyright MMVI Anselm R. Garbe <garbeam at gmail dot com>
(C)opyright MMVI Sander van Dijk <a dot h dot vandijk at gmail dot com>

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the 
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in 
all copies or substantial portions of the Software. 

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL 
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
DEALINGS IN THE SOFTWARE.
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-11-15 05:45:52 +0000
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# Helpers for Unicode.
#
# Mu has no characters, only code points and graphemes.
# Code points are the indivisible atoms of text streams.
#   https://en.wikipedia.org/wiki/Code_point
# Graphemes are the smallest self-contained unit of text.
# Graphemes may consist of multiple code points.
#
# Mu graphemes are always represented in utf-8, and they are required to fit
# in 4 bytes.
#
# Mu doesn't currently support combining code points, or graphemes made of
# multiple code points. One day we will.
# We also don't currently support code points that translate into multiple
# or wide graphemes. (In particular, Tab will never be supported.)

# transliterated from tb_utf8_unicode_to_char in https://github.com/nsf/termbox
# https://wiki.tcl-lang.org/page/UTF%2D8+bit+by+bit explains the algorithm
#
# The day we want to support combining characters, this function will need to
# take multiple code points. Or something.
fn to-grapheme in: code-point -> _/eax: grapheme {
  var c/eax: int <- copy in
  var num-trailers/ecx: int <- copy 0
  var first/edx: int <- copy 0
  $to-grapheme:compute-length: {
    # single byte: just return it
    compare c, 0x7f
    {
      break-if->
      var g/eax: grapheme <- copy c
      return g
    }
    # 2 bytes
    compare c, 0x7ff
    {
      break-if->
      num-trailers <- copy 1
      first <- copy 0xc0
      break $to-grapheme:compute-length
    }
    # 3 bytes
    compare c, 0xffff
    {
      break-if->
      num-trailers <- copy 2
      first <- copy 0xe0
      break $to-grapheme:compute-length
    }
    # 4 bytes
    compare c, 0x1fffff
    {
      break-if->
      num-trailers <- copy 3
      first <- copy 0xf0
      break $to-grapheme:compute-length
    }
    # more than 4 bytes: unsupported
    # TODO: print to stderr
    compare c, 0x1fffff
    {
      break-if->
      print-string-to-real-screen "unsupported code point "
      print-int32-hex-to-real-screen c
      print-string-to-real-screen "\n"
      var exit-status/ebx: int <- copy 1
      syscall_exit
    }
  }
  # emit trailer bytes, 6 bits from 'in', first two bits '10'
  var result/edi: grapheme <- copy 0
  {
    compare num-trailers, 0
    break-if-<=
    var tmp/esi: int <- copy c
    tmp <- and 0x3f
    tmp <- or 0x80
    result <- shift-left 8
    result <- or tmp
    # update loop state
    c <- shift-right 6
    num-trailers <- decrement
    loop
  }
  # emit engine
  result <- shift-left 8
  result <- or c
  result <- or first
  #
  return result
}

# single-byte code point have identical graphemes
fn test-to-grapheme-single-byte {
  var in-int/ecx: int <- copy 0
  {
    compare in-int, 0x7f
    break-if->
    var in/eax: code-point <- copy in-int
    var out/eax: grapheme <- to-grapheme in
    var out-int/eax: int <- copy out
    check-ints-equal out-int, in-int, "F - test-to-grapheme-single-byte"
    in-int <- increment
    loop
  }
}

                                                              # byte       | byte      | byte      | byte
# smallest 2-byte utf-8
fn test-to-grapheme-two-bytes-min {
  var in/eax: code-point <- copy 0x80                         #                                 10     00-0000
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0x80c2, "F - to-grapheme/2a"      #                         110 0-0010  10 00-0000
}

# largest 2-byte utf-8
fn test-to-grapheme-two-bytes-max {
  var in/eax: code-point <- copy 0x7ff                        #                             1-1111     11-1111
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0xbfdf, "F - to-grapheme/2b"      #                         110 1-1111  10 11-1111
}

# smallest 3-byte utf-8
fn test-to-grapheme-three-bytes-min {
  var in/eax: code-point <- copy 0x800                        #                            10-0000     00-0000
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0x80a0e0, "F - to-grapheme/3a"    #              1110 0000  10 10-0000  10 00-0000
}

# largest 3-byte utf-8
fn test-to-grapheme-three-bytes-max {
  var in/eax: code-point <- copy 0xffff                       #                   1111     11-1111     11-1111
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0xbfbfef, "F - to-grapheme/3b"    #              1110 1111  10 11-1111  10 11-1111
}

# smallest 4-byte utf-8
fn test-to-grapheme-four-bytes-min {
  var in/eax: code-point <- copy 0x10000                      #                 1-0000     00-0000     00-0000
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0x808090f0, "F - to-grapheme/4a"  # 1111-0 000  10 01-0000  10 00-0000  10 00-0000
}

# largest 4-byte utf-8
fn test-to-grapheme-four-bytes-max {
  var in/eax: code-point <- copy 0x1fffff                     #        111     11-1111     11-1111     11-1111
  var out/eax: grapheme <- to-grapheme in
  var out-int/eax: int <- copy out
  check-ints-equal out-int, 0xbfbfbff7, "F - to-grapheme/4b"  # 1111-0 111  10 11-1111  10 11-1111  10 11-1111
}

# read the next grapheme from a stream of bytes
fn read-grapheme in: (addr stream byte) -> _/eax: grapheme {
  # if at eof, return EOF
  {
    var eof?/eax: boolean <- stream-empty? in
    compare eof?, 0  # false
    break-if-=
    return 0xffffffff
  }
  var c/eax: byte <- read-byte in
  var num-trailers/ecx: int <- copy 0
  $read-grapheme:compute-length: {
    # single byte: just return it
    compare c, 0xc0
    {
      break-if->=
      var g/eax: grapheme <- copy c
      return g
    }
    compare c, 0xfe
    {
      break-if-<
      var g/eax: grapheme <- copy c
      return g
    }
    # 2 bytes
    compare c, 0xe0
    {
      break-if->=
      num-trailers <- copy 1
      break $read-grapheme:compute-length
    }
    # 3 bytes
    compare c, 0xf0
    {
      break-if->=
      num-trailers <- copy 2
      break $read-grapheme:compute-length
    }
    # 4 bytes
    compare c, 0xf8
    {
      break-if->=
      num-trailers <- copy 3
      break $read-grapheme:compute-length
    }
$read-grapheme:abort: {
      # TODO: print to stderr
      print-string-to-real-screen "utf-8 encodings larger than 4 bytes are not supported. First byte seen: "
      var n/eax: int <- copy c
      print-int32-hex-to-real-screen n
      print-string-to-real-screen "\n"
      var exit-status/ebx: int <- copy 1
      syscall_exit
    }
  }
  # prepend trailer bytes
  var result/edi: grapheme <- copy c
  var num-byte-shifts/edx: int <- copy 1
  {
    compare num-trailers, 0
    break-if-<=
    var tmp/eax: byte <- read-byte in
    var tmp2/eax: int <- copy tmp
    tmp2 <- shift-left-bytes tmp2, num-byte-shifts
    result <- or tmp2
    # update loop state
    num-byte-shifts <- increment
    num-trailers <- decrement
    loop
  }
  return result
}

fn test-read-grapheme {
  var s: (stream byte 0x30)
  var s2/ecx: (addr stream byte) <- address s
  write s2, "aΒc世d界e"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x61, "F - test grapheme/0"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x92ce, "F - test grapheme/1"  # greek capital letter beta
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x63, "F - test grapheme/2"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x96b8e4, "F - test grapheme/3"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x64, "F - test grapheme/4"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x8c95e7, "F - test grapheme/5"
  var c/eax: grapheme <- read-grapheme s2
  var n/eax: int <- copy c
  check-ints-equal n, 0x65, "F - test grapheme/6"
}

fn read-grapheme-buffered in: (addr buffered-file) -> _/eax: grapheme {
  var c/eax: byte <- read-byte-buffered in
  var num-trailers/ecx: int <- copy 0
  $read-grapheme-buffered:compute-length: {
    # single byte: just return it
    compare c, 0xc0
    {
      break-if->=
      var g/eax: grapheme <- copy c
      return g
    }
    compare c, 0xfe
    {
      break-if-<
      var g/eax: grapheme <- copy c
      return g
    }
    # 2 bytes
    compare c, 0xe0
    {
      break-if->=
      num-trailers <- copy 1
      break $read-grapheme-buffered:compute-length
    }
    # 3 bytes
    compare c, 0xf0
    {
      break-if->=
      num-trailers <- copy 2
      break $read-grapheme-buffered:compute-length
    }
    # 4 bytes
    compare c, 0xf8
    {
      break-if->=
      num-trailers <- copy 3
      break $read-grapheme-buffered:compute-length
    }
$read-grapheme-buffered:abort: {
      # TODO: print to stderr
      print-string-to-real-screen "utf-8 encodings larger than 4 bytes are not supported. First byte seen: "
      var n/eax: int <- copy c
      print-int32-hex-to-real-screen n
      print-string-to-real-screen "\n"
      var exit-status/ebx: int <- copy 1
      syscall_exit
    }
  }
  # prepend trailer bytes
  var result/edi: grapheme <- copy c
  var num-byte-shifts/edx: int <- copy 1
  {
    compare num-trailers, 0
    break-if-<=
    var tmp/eax: byte <- read-byte-buffered in
    var tmp2/eax: int <- copy tmp
    tmp2 <- shift-left-bytes tmp2, num-byte-shifts
    result <- or tmp2
    # update loop state
    num-byte-shifts <- increment
    num-trailers <- decrement
    loop
  }
  return result
}

# needed because available primitives only shift by a literal/constant number of bits
fn shift-left-bytes n: int, k: int -> _/eax: int {
  var i/ecx: int <- copy 0
  var result/eax: int <- copy n
  {
    compare i, k
    break-if->=
    compare i, 4  # only 4 bytes in 32 bits
    break-if->=
    result <- shift-left 8
    i <- increment
    loop
  }
  return result
}

fn test-shift-left-bytes-0 {
  var result/eax: int <- shift-left-bytes 1, 0
  check-ints-equal result, 1, "F - shift-left-bytes 0"
}

fn test-shift-left-bytes-1 {
  var result/eax: int <- shift-left-bytes 1, 1
  check-ints-equal result, 0x100, "F - shift-left-bytes 1"
}

fn test-shift-left-bytes-2 {
  var result/eax: int <- shift-left-bytes 1, 2
  check-ints-equal result, 0x10000, "F - shift-left-bytes 2"
}

fn test-shift-left-bytes-3 {
  var result/eax: int <- shift-left-bytes 1, 3
  check-ints-equal result, 0x1000000, "F - shift-left-bytes 3"
}

fn test-shift-left-bytes-4 {
  var result/eax: int <- shift-left-bytes 1, 4
  check-ints-equal result, 0, "F - shift-left-bytes 4"
}

fn test-shift-left-bytes-5 {
  var result/eax: int <- shift-left-bytes 1, 5
  check-ints-equal result, 0, "F - shift-left-bytes >4"
}

# To run all tests, uncomment this and run:
#   $ ./translate_mu  &&  ./a.elf
#? fn main -> _/ebx: int {
#?   run-tests
#?   r <- copy 0
#? }

# write a grapheme to a stream of bytes
# this is like write-to-stream, except we skip leading 0 bytes
fn write-grapheme out: (addr stream byte), g: grapheme {
$write-grapheme:body: {
  var c/eax: int <- copy g
  append-byte out, c  # first byte is always written
  c <- shift-right 8
  compare c, 0
  break-if-= $write-grapheme:body
  append-byte out, c
  c <- shift-right 8
  compare c, 0
  break-if-= $write-grapheme:body
  append-byte out, c
  c <- shift-right 8
  compare c, 0
  break-if-= $write-grapheme:body
  append-byte out, c
}
}
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-11-15 05:45:50 +0000