Bitwise IO: Difference between revisions
Added Wren
(Changed ".. <" (no longer a valid syntax) to "..<". Added missing "dec dataCtr" in the last loop.) |
(Added Wren) |
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the file containing the crunched text is 65 bytes
the expanded string is the same as the original</pre>
=={{header|Wren}}==
{{trans|Kotlin}}
<lang ecmascript>import "io" for File
class BitFilter {
construct new(name) {
_name = name
_accu = 0
_bits = 0
}
openWriter() {
_bw = File.create(_name)
}
openReader() {
_br = File.open(_name)
_offset = 0
}
write(buf, start, nBits, shift) {
var index = start + (shift/8).floor
shift = shift % 8
while (nBits != 0 || _bits >= 8) {
while (_bits >= 8) {
_bits = _bits - 8
_bw.writeBytes(String.fromByte((_accu >> _bits) & 255))
}
while (_bits < 8 && nBits != 0) {
var b = buf[index]
_accu = (_accu << 1) | (((128 >> shift) & b) >> (7 - shift))
nBits = nBits - 1
_bits = _bits + 1
shift = shift + 1
if (shift == 8) {
shift = 0
index = index + 1
}
}
}
}
read(buf, start, nBits, shift) {
var index = start + (shift/8).floor
shift = shift % 8
while (nBits != 0) {
while (_bits != 0 && nBits != 0) {
var mask = 128 >> shift
if ((_accu & (1 << (_bits - 1))) != 0) {
buf[index] = (buf[index] | mask) & 255
} else {
buf[index] = (buf[index] & ~mask) & 255
}
nBits = nBits - 1
_bits = _bits - 1
shift = shift + 1
if (shift >= 8) {
shift = 0
index = index + 1
}
}
if (nBits == 0) break
var byte = _br.readBytes(1, _offset).bytes[0]
_accu = (_accu << 8) | byte
_bits = _bits + 8
_offset = _offset + 1
}
}
closeWriter() {
if (_bits != 0) {
_accu = _accu << (8 - _bits)
_bw.writeBytes(String.fromByte(_accu & 255))
}
_bw.close()
_accu = 0
_bits = 0
}
closeReader() {
_br.close()
_accu = 0
_bits = 0
_offset = 0
}
}
var s = "abcdefghijk".bytes.toList
var f = "test.bin"
var bf = BitFilter.new(f)
/* for each byte in s, write 7 bits skipping 1 */
bf.openWriter()
for (i in 0...s.count) bf.write(s, i, 7, 1)
bf.closeWriter()
/* read 7 bits and expand to each byte of s2 skipping 1 bit */
bf.openReader()
var s2 = List.filled(s.count, 0)
for (i in 0...s2.count) bf.read(s2, i, 7, 1)
bf.closeReader()
System.print(s2.map { |b| String.fromByte(b) }.join())</lang>
{{out}}
<pre>
abcdefghijk
</pre>
=={{header|zkl}}==
| |||