September Morn Update

Task/Bitwise-IO/00DESCRIPTION

@@ -1,6 +1,6 @@
 The aim of this task is to write functions (or create a class if your
 language is Object Oriented and you prefer) for reading and writing sequences of
-bits. While the output of a <tt>asciiprint "STRING"</tt> is the ASCII byte sequence
+bits, most significant bit first. While the output of a <tt>asciiprint "STRING"</tt> is the ASCII byte sequence
 "S", "T", "R", "I", "N", "G", the output of a "print" of the bits sequence
 0101011101010 (13 bits) must be 0101011101010; real I/O is performed always
 ''quantized'' by byte (avoiding endianness issues and relying on underlying

Task/Bitwise-IO/Julia/bitwise-io.julia

@@ -0,0 +1,48 @@
+function compress7(inio, outio)
+    nextwritebyte = read(inio, UInt8) & 0x7f
+    filled = 7
+    while !eof(inio)
+        inbyte = read(inio, UInt8)
+        write(outio, UInt8(nextwritebyte | inbyte << filled))
+        nextwritebyte = inbyte >> (8 - filled)
+        filled = (filled + 7) % 8
+        if filled == 0
+            if eof(inio)
+                break
+            end
+            nextwritebyte = read(inio, UInt8) & 0x7f
+            filled = 7
+        end
+    end
+    if filled != 0
+        write(outio, UInt8(nextwritebyte))
+    end
+end
+
+function expand7(inio, outio)
+    newbyte = read(inio, UInt8)
+    write(outio, UInt8(newbyte & 0x7f))
+    residualbyte::UInt8 = newbyte >> 7
+    filled = 1
+    while !eof(inio)
+        inbyte = read(inio, UInt8)
+        write(outio, UInt8((residualbyte | inbyte << filled) & 0x7f))
+        residualbyte = inbyte >> (7 - filled)
+        filled = (filled + 1) % 7
+        if filled == 0
+            write(outio, UInt8(residualbyte & 0x7f))
+            residualbyte = 0
+        end
+    end
+end
+
+str = b"These bit oriented I/O functions can be used to implement compressors and decompressors."
+ins = IOBuffer(str)
+outs = IOBuffer()
+newouts = IOBuffer()
+compress7(ins, outs)
+seek(outs,0)
+expand7(outs, newouts)
+println("Initial string of length $(length(str)): ", String(ins.data))
+println("Compressed to length $(length(outs.data)) on line below:\n", String(outs.data))
+println("Decompressed string: ", String(newouts.data))

Task/Bitwise-IO/Phix/bitwise-io.phix

@@ -0,0 +1,103 @@
+enum FN, V, BITS -- fields of a bitwiseioreader/writer
+
+function new_bitwiseio(string filename, mode)
+    integer fn = open(filename,mode)
+    return {fn,0,0}     -- ie {FN,V=0,BITS=0}
+end function
+
+function new_bitwiseiowriter(string filename)
+    return new_bitwiseio(filename,"wb")
+end function
+
+function new_bitwiseioreader(string filename)
+    return new_bitwiseio(filename,"rb")
+end function
+
+function write_bits(sequence writer, integer v, bits)
+    integer {fn,wv,wb} = writer,
+            p2 = power(2,bits), ch
+    if v!=and_bits(v,p2*2-1) then ?9/0 end if
+    wv = wv*p2+v
+    wb += bits
+    while wb>=8 do
+        wb -= 8
+        p2 = power(2,wb)
+        ch = floor(wv/p2)
+        puts(fn,ch)
+        wv -= ch*p2
+    end while
+    if wv>=#100 then ?9/0 end if
+    if wb>=8 then ?9/0 end if
+    writer[V]= wv
+    writer[BITS]= wb
+    return writer
+end function
+
+function close_bitwiseiowriter(sequence writer)
+    integer {fn,wv,wb} = writer
+    if wb then
+        if wb>=8 then ?9/0 end if -- sanity check
+        writer = write_bits(writer,0,8-wb)
+    end if
+    if writer[V]!=0 then ?9/0 end if
+    if writer[BITS]!=0 then ?9/0 end if
+    close(fn)
+    writer[FN]=-1
+    return writer
+end function
+
+function read_bits(sequence reader, integer bits)
+    integer {fn,rv,rb} = reader, ch, p2
+    while bits>rb do
+        ch = getc(fn)
+        if ch=-1 then return {-1,reader} end if
+        rv = rv*#100+ch
+        rb += 8
+    end while
+    rb -= bits
+    p2 = power(2,rb)
+    ch = floor(rv/p2)
+    rv -= ch*p2
+    reader[V]= rv
+    reader[BITS]= rb
+    return {ch,reader}
+end function
+
+function as_hexb(string s, fmt="%02x ")
+-- helper funtion, returns hex string, or binary if fmt="%08b "
+    string res = ""
+    for i=1 to length(s) do
+        res &= sprintf(fmt,s[i])
+    end for
+    return trim(res)
+end function
+
+constant test = "This is a test."
+--constant test = "This is a test"
+--constant test = "abcdefghijk"
+--constant test = "STRING"
+--constant test = "This is an ascii string that will be crunched, written, read and expanded."
+printf(1,"\"%s\" as bytes: %s (length %d)\n",{test,as_hexb(test),length(test)})
+printf(1,"    original bits: %s\n",{as_hexb(test,"%08b ")})
+
+sequence writer = new_bitwiseiowriter("test.bin")
+for i=1 to length(test) do
+    writer = write_bits(writer,test[i],7)
+end for
+writer = close_bitwiseiowriter(writer)
+
+integer fn = open("test.bin","rb")
+string bytes = get_text(fn,GT_WHOLE_FILE)
+printf(1,"Written bitstream: %s\n",{as_hexb(bytes,"%08b ")})
+printf(1,"Written bytes: %s (length %d)\n",{as_hexb(bytes),length(bytes)})
+close(fn)
+
+sequence reader = new_bitwiseioreader("test.bin")
+bytes = ""
+integer ch
+while true do
+    {ch,reader} = read_bits(reader,7)
+    if ch=-1 then exit end if
+    bytes &= ch
+end while
+printf(1,"\"%s\" as bytes: %s (length %d)\n",{bytes,as_hexb(bytes),length(bytes)})

Task/Bitwise-IO/Seed7/bitwise-io.seed7

@@ -0,0 +1,60 @@
+$ include "seed7_05.s7i";
+  include "bitdata.s7i";
+  include "strifile.s7i";
+
+const proc: initWriteAscii (inout file: outFile, inout integer: bitPos) is func
+  begin
+    outFile.bufferChar := '\0;';
+    bitPos := 0;
+  end func;
+
+const proc: writeAscii (inout file: outFile, inout integer: bitPos, in string: ascii) is func
+  local
+    var char: ch is ' ';
+  begin
+    for ch range ascii do
+      if ch > '\127;' then
+        raise RANGE_ERROR;
+      else
+        putBitsMsb(outFile, bitPos, ord(ch), 7);
+      end if;
+    end for;
+  end func;
+
+const proc: finishWriteAscii (inout file: outFile, inout integer: bitPos) is func
+  begin
+    write(outFile, chr(ord(outFile.bufferChar)));
+  end func;
+
+const proc: initReadAscii (inout file: outFile, inout integer: bitPos) is func
+  begin
+    bitPos := 8;
+  end func;
+
+const func string: readAscii (inout file: inFile, inout integer: bitPos, in integer: length) is func
+  result
+    var string: stri is "";
+  local
+    var char: ch is ' ';
+  begin
+    while not eof(inFile) and length(stri) < length do
+      ch := chr(getBitsMsb(inFile, bitPos, 7));
+      if inFile.bufferChar <> EOF then
+        stri &:= ch;
+      end if;
+    end while;
+  end func;
+
+const proc: main is func
+  local
+    var file: aFile is STD_NULL;
+    var integer: bitPos is 0;
+  begin
+    aFile := openStrifile;
+    initWriteAscii(aFile, bitPos);
+    writeAscii(aFile, bitPos, "Hello, Rosetta Code!");
+    finishWriteAscii(aFile, bitPos);
+    seek(aFile, 1);
+    initReadAscii(aFile, bitPos);
+    writeln(literal(readAscii(aFile, bitPos, 100)));
+  end func;