quirinpa · April 9, 2016 22:07 · Apr 9, 2016 · Mar 30, 2016 · Mar 27, 2016
diff --git a/fileb.h b/fileb.h
@@ -65,7 +65,7 @@ void fwriteb(void *restrict ptr, size_t sizeb, size_t rSizeb, FILE *fp, bitCurso
 				 firstRelevantByte = firstRelevantBit / 8,
 				 distanceToStartOfByte = firstRelevantBit - firstRelevantByte * 8;
 
-	unsigned char *pchar = (unsigned char*)ptr + firstRelevantByte;	
+	unsigned char *pchar = (unsigned char*)ptr + firstRelevantByte;	// Assuming little Endian
 
 	size_t bitsToWrite = sizeb,
 				 bitsToAdd;

diff --git a/fileb.h b/fileb.h
@@ -106,7 +106,7 @@ void fcloseb(FILE *fp, bitCursor *c) {
 	fwrite(&curData, 1, 1, fp);
 }
 
-/* Reads a number of bits from a file
+/* Reads a number of bits from a file (it is your responsibility to init the var as 0)
  *
  * @param ptr a pointer to the variable in which to write data that is read
  * @param sizeb the number of bits to be read
@@ -121,7 +121,6 @@ void freadb(void *restrict ptr, size_t sizeb, size_t rSizeb, FILE *fp, bitCursor
 				 distanceToStartOfByte = firstRelevantBit - firstRelevantByte*8;
 
 	unsigned char *pchar = (unsigned char*)ptr + firstRelevantByte;
-	*pchar = 0;
 
 	size_t bitsToRead = sizeb,
 				 bitsToAdd,

diff --git a/fileb.h b/fileb.h
@@ -0,0 +1,154 @@
+/* fileb.h - write/read files bit by bit
+ * 
+ * MIT License
+ *
+ * Copyright (c) 2016 Paulo André Azevedo Quirino
+ *
+ * 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.
+ *
+ * quirinpa@gmail.com 
+ */
+
+#ifndef FILEB_H
+#define FILEB_H
+
+#include <stdio.h>
+
+typedef struct bCursor {
+	unsigned char d;
+	size_t s;
+} bitCursor;
+
+/* creates a new bitCursor object with default values
+ * (needed for starting bit-wise read/write operations,
+ * a pointer to that same cursor must then be provided
+ * to subsequent read/write operations until all data is
+ * read/written)
+ *
+ * @returns cursor with default values
+ */
+bitCursor newBitCursor() {
+	bitCursor c = {0, 0};
+	return c;
+}
+
+#define curBusySpace c->s
+#define curData c->d
+
+/* Writes a number of bits into a file
+ *
+ * @param ptr a pointer to the variable containing the data to be written
+ * @param sizeb the number of bits to be written
+ * @param rSizeb the real size of the variable in bits
+ * @param fp a pointer to the file
+ * @param c a pointer to a bitCursor (possibly containing bits from the last variable written)
+ */
+void fwriteb(void *restrict ptr, size_t sizeb, size_t rSizeb, FILE *fp, bitCursor *c) {
+
+	size_t firstRelevantBit = rSizeb - sizeb,
+				 firstRelevantByte = firstRelevantBit / 8,
+				 distanceToStartOfByte = firstRelevantBit - firstRelevantByte * 8;
+
+	unsigned char *pchar = (unsigned char*)ptr + firstRelevantByte;	
+
+	size_t bitsToWrite = sizeb,
+				 bitsToAdd;
+
+readywrite:
+	bitsToAdd = 8 - (curBusySpace > distanceToStartOfByte ? curBusySpace : distanceToStartOfByte);
+
+	curData |= (*pchar << distanceToStartOfByte) >> curBusySpace;
+
+	curBusySpace += bitsToAdd;
+	if (curBusySpace >= 8) {
+		fwrite(&curData, 1, 1, fp);
+		curBusySpace = curData = 0;
+	}
+
+	bitsToWrite -= bitsToAdd;
+	if (bitsToWrite <= 0) return;
+
+	distanceToStartOfByte += bitsToAdd;
+
+	if (distanceToStartOfByte >= 8) {
+		distanceToStartOfByte = 0;
+		pchar++;
+	}
+
+	goto readywrite;
+}
+
+
+/* Writes the remaining bits after a sequence of fwriteb operations
+ * (required for correct behaviour)
+ *
+ * @param fp a pointer to the file
+ * @param c a pointer to a bitCursor (possibly containing bits from the last variable written)
+ */
+void fcloseb(FILE *fp, bitCursor *c) {
+	if (curBusySpace <= 0) return;
+	fwrite(&curData, 1, 1, fp);
+}
+
+/* Reads a number of bits from a file
+ *
+ * @param ptr a pointer to the variable in which to write data that is read
+ * @param sizeb the number of bits to be read
+ * @param rSizeb the real size of the variable in bits
+ * @param fp a pointer to the file
+ * @param c a pointer to a bitCursor (possibly containing bits from the last read Byte)
+ */
+void freadb(void *restrict ptr, size_t sizeb, size_t rSizeb, FILE *fp, bitCursor *c) {
+
+	size_t firstRelevantBit = rSizeb - sizeb,
+				 firstRelevantByte = firstRelevantBit / 8,
+				 distanceToStartOfByte = firstRelevantBit - firstRelevantByte*8;
+
+	unsigned char *pchar = (unsigned char*)ptr + firstRelevantByte;
+	*pchar = 0;
+
+	size_t bitsToRead = sizeb,
+				 bitsToAdd,
+				 availableBits = 8 - distanceToStartOfByte;
+
+readyread:
+	if (curBusySpace <= 0) {
+		fread(&curData, 1, 1, fp);
+		curBusySpace = 8;
+	}
+
+	bitsToAdd = curBusySpace > availableBits ? availableBits : curBusySpace;
+	(*pchar) |= curData >> distanceToStartOfByte;
+
+	curData <<= bitsToAdd;
+	curBusySpace -= bitsToAdd;
+	bitsToRead -= bitsToAdd;
+	if (bitsToRead <= 0) return;
+
+	distanceToStartOfByte += bitsToAdd;
+	if (distanceToStartOfByte >= 8) {
+		distanceToStartOfByte = 0;
+		pchar++;
+	}
+	availableBits = 8 - distanceToStartOfByte;
+
+	goto readyread;
+}
+
+#endif