Bitwise IO: Difference between revisions
Added Kotlin
(→{{header|Python}}: Implement context manager protocol so classes can be use with a "with" statement.) |
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69</lang>
Note: this implementation writes the bytes to the session (which is to say, it just gets displayed like any other result. Also, the compressed result is represented as bits - like 1 0 1 0 1... You'll of course need other code when you want to do other things.)
=={{header|Kotlin}}==
{{trans|C}}
<lang scala>// version 1.2.31
import java.io.File
class BitFilter(val f: File, var accu: Int = 0, var bits: Int = 0) {
private val bw = f.bufferedWriter()
private val br = f.bufferedReader()
fun write(buf: ByteArray, start: Int, _nBits: Int, _shift: Int) {
var nBits = _nBits
var index = start + _shift / 8
var shift = _shift % 8
while (nBits != 0 || bits >= 8) {
while (bits >= 8) {
bits -= 8
bw.write(accu ushr bits)
accu = accu and ((1 shl bits) - 1)
}
while (bits < 8 && nBits != 0) {
val b = buf[index].toInt()
accu = (accu shl 1) or (((128 ushr shift) and b) ushr (7 - shift))
nBits--
bits++
if (++shift == 8) { shift = 0; index++ }
}
}
}
fun read(buf: ByteArray, start: Int, _nBits: Int, _shift: Int) {
var nBits = _nBits
var index = start + _shift / 8
var shift = _shift % 8
while (nBits != 0) {
while (bits != 0 && nBits != 0) {
val mask = 128 ushr shift
if ((accu and (1 shl (bits - 1))) != 0)
buf[index] = (buf[index].toInt() or mask).toByte()
else
buf[index] = (buf[index].toInt() and mask.inv()).toByte()
nBits--
bits--
if (++shift >= 8) { shift = 0; index++ }
}
if (nBits == 0) break
accu = (accu shl 8) or br.read()
bits += 8
}
}
fun closeWriter() {
if (bits != 0) {
accu = (accu shl (8 - bits))
bw.write(accu)
}
bw.close()
accu = 0
bits = 0
}
fun closeReader() {
br.close()
accu = 0
bits = 0
}
}
fun main(args: Array<String>) {
val s = "abcdefghijk".toByteArray(Charsets.UTF_8)
val f = File("test.bin")
val bf = BitFilter(f)
/* for each byte in s, write 7 bits skipping 1 */
for (i in 0 until s.size) bf.write(s, i, 7, 1)
bf.closeWriter()
/* read 7 bits and expand to each byte of s2 skipping 1 bit */
val s2 = ByteArray(s.size)
for (i in 0 until s2.size) bf.read(s2, i, 7, 1)
bf.closeReader()
println(String(s2, Charsets.UTF_8))
}</lang>
{{out}}
<pre>
abcdefghijk
</pre>
=={{header|Lingo}}==
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