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Diffstat (limited to 'baremetal/403unicode.mu')
| -rw-r--r-- | baremetal/403unicode.mu | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/baremetal/403unicode.mu b/baremetal/403unicode.mu deleted file mode 100644 index 6ec30c3d..00000000 --- a/baremetal/403unicode.mu +++ /dev/null @@ -1,193 +0,0 @@ -# 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 error message to stderr - compare c, 0x1fffff - { - break-if-> - return 0 - } - } - # 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 -} - -# TODO: bring in tests once we have check-ints-equal - -# 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 $read-grapheme:compute-length - } - # TODO: print error message - return 0 - } - # prepend trailer bytes - var result/edi: grapheme <- copy c - var num-byte-shifts/edx: int <- copy 1 - { - compare num-trailers, 0 - break-if-<= - var tmp/eax: byte <- read-byte in - var tmp2/eax: int <- copy tmp - tmp2 <- shift-left-bytes tmp2, num-byte-shifts - result <- or tmp2 - # update loop state - num-byte-shifts <- increment - num-trailers <- decrement - loop - } - return result -} - -# needed because available primitives only shift by a literal/constant number of bits -fn shift-left-bytes n: int, k: int -> _/eax: int { - var i/ecx: int <- copy 0 - var result/eax: int <- copy n - { - compare i, k - break-if->= - compare i, 4 # only 4 bytes in 32 bits - break-if->= - result <- shift-left 8 - i <- increment - loop - } - return result -} - -# write a grapheme to a stream of bytes -# this is like write-to-stream, except we skip leading 0 bytes -fn write-grapheme out: (addr stream byte), g: grapheme { -$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 -} -} |