/* * bit-io.c: Buffered and bit oriented file I/O * * Written by: Ullrich Hafner * * This file is part of FIASCO («F»ractal «I»mage «A»nd «S»equence «CO»dec) * Copyright (C) 1994-2000 Ullrich Hafner */ /* * $Date: 2000/06/14 20:49:37 $ * $Author: hafner $ * $Revision: 5.1 $ * $State: Exp $ */ #define _BSD_SOURCE 1 /* Make sure strdup() is in string.h */ #define _XOPEN_SOURCE 500 /* Make sure strdup() is in string.h */ #include "config.h" #include #if STDC_HEADERS # include #endif /* not STDC_HEADERS */ #include "macros.h" #include "types.h" #include "error.h" #include "misc.h" #include "bit-io.h" /***************************************************************************** local constants *****************************************************************************/ static const unsigned BUFFER_SIZE = 16350; static const unsigned mask[] = {0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000, 0x8000}; /***************************************************************************** public code *****************************************************************************/ FILE * open_file (const char *filename, const char *env_var, openmode_e mode) /* * Try to open file 'filename' with mode 'mode' (READ_ACCESS, WRITE_ACCESS). * Scan the current directory first and then cycle through the * path given in the environment variable 'env_var', if set. * * Return value: * Pointer to open file on success, else NULL. */ { char *path; /* current path */ FILE *fp; /* file pointer of I/O stream */ char *ext_filename = NULL; /* full path of file */ char *env_path = NULL; /* path given by 'env_var' */ char const * const PATH_SEP = " ;:,"; /* path separation characters */ char const * const DEFAULT_PATH = "."; /* default for output files */ const char * const read_mode = "rb"; const char * const write_mode = "wb"; assert (mode == READ_ACCESS || mode == WRITE_ACCESS); /* * First check for stdin or stdout */ if (filename == NULL || streq (filename, "-")) { if (mode == READ_ACCESS) return stdin; else return stdout; } /* * Try to open 'readonly' file in the current directory */ if (mode == READ_ACCESS && (fp = fopen (filename, read_mode))) return fp; if (mode == WRITE_ACCESS && strchr (filename, '/')) /* contains path */ return fopen (filename, write_mode); /* * Get value of environment variable 'env_var', if set * else use DEFAULT_PATH ("./") */ if (env_var != NULL) env_path = getenv (env_var); if (env_path == NULL) env_path = strdup (DEFAULT_PATH); else env_path = strdup (env_path); /* * Try to open file in the directory given by the environment * variable env_var - individual path components are separated by PATH_SEP */ path = strtok (env_path, PATH_SEP); do { if (ext_filename) Free (ext_filename); ext_filename = Calloc (strlen (path) + strlen (filename) + 2, sizeof (char)); strcpy (ext_filename, path); if (*(ext_filename + strlen (ext_filename) - 1) != '/') strcat (ext_filename, "/"); strcat (ext_filename, filename); fp = fopen (ext_filename, mode == READ_ACCESS ? read_mode : write_mode); } while (fp == NULL && (path = strtok (NULL, PATH_SEP)) != NULL); Free (env_path); return fp; } bitfile_t * open_bitfile (const char *filename, const char *env_var, openmode_e mode) /* * Bitfile constructor: * Try to open file 'filename' for buffered bit oriented access with mode * 'mode'. Scan the current directory first and then cycle through the path * given in the environment variable 'env_var', if set. * * Return value: * Pointer to open bitfile on success, * otherwise the program is terminated. */ { bitfile_t *bitfile = Calloc (1, sizeof (bitfile_t)); bitfile->file = open_file (filename, env_var, mode); if (bitfile->file == NULL) file_error (filename); if (mode == READ_ACCESS) { bitfile->bytepos = 0; bitfile->bitpos = 0; bitfile->mode = mode; bitfile->filename = filename ? strdup (filename) : strdup ("(stdin)"); } else if (mode == WRITE_ACCESS) { bitfile->bytepos = BUFFER_SIZE - 1; bitfile->bitpos = 8; bitfile->mode = mode; bitfile->filename = filename ? strdup (filename) : strdup ("(stdout)"); } else error ("Unknow file access mode '%d'.", mode); bitfile->bits_processed = 0; bitfile->buffer = Calloc (BUFFER_SIZE, sizeof (byte_t)); bitfile->ptr = bitfile->buffer; return bitfile; } bool_t get_bit (bitfile_t *bitfile) /* * Get one bit from the given stream 'bitfile'. * * Return value: * 1 H bit * 0 L bit * * Side effects: * Buffer of 'bitfile' is modified accordingly. */ { assert (bitfile); if (!bitfile->bitpos--) /* use next byte ? */ { bitfile->ptr++; if (!bitfile->bytepos--) /* no more bytes left in the buffer? */ { /* * Fill buffer with new data */ int bytes = fread (bitfile->buffer, sizeof (byte_t), BUFFER_SIZE, bitfile->file) - 1; if (bytes < 0) /* Error or EOF */ error ("Can't read next bit from bitfile %s.", bitfile->filename); else bitfile->bytepos = bytes; bitfile->ptr = bitfile->buffer; } bitfile->bitpos = 7; } bitfile->bits_processed++; return *bitfile->ptr & mask [bitfile->bitpos] ? 1 : 0; } unsigned int get_bits (bitfile_t *bitfile, unsigned bits) /* * Get #'bits' bits from the given stream 'bitfile'. * * Return value: * composed integer value * * Side effects: * Buffer of 'bitfile' is modified. */ { unsigned value = 0; /* input value */ while (bits--) value = (unsigned) (value << 1) | get_bit (bitfile); return value; } void put_bit (bitfile_t *bitfile, unsigned value) /* * Put the bit 'value' to the bitfile buffer. * The buffer is written to the file 'bitfile->file' if the number of * buffer bytes exceeds 'BUFFER_SIZE'. * * No return value. * * Side effects: * Buffer of 'bitfile' is modified. */ { assert (bitfile); if (!bitfile->bitpos--) /* use next byte ? */ { bitfile->ptr++; if (!bitfile->bytepos--) /* no more bytes left ? */ { /* * Write buffer to disk and fill buffer with zeros */ if (fwrite (bitfile->buffer, sizeof (byte_t), BUFFER_SIZE, bitfile->file) != BUFFER_SIZE) error ("Can't write next bit of bitfile %s!", bitfile->filename); memset (bitfile->buffer, 0, BUFFER_SIZE); bitfile->bytepos = BUFFER_SIZE - 1; bitfile->ptr = bitfile->buffer; } bitfile->bitpos = 7; } if (value) *bitfile->ptr |= mask [bitfile->bitpos]; bitfile->bits_processed++; } void put_bits (bitfile_t *bitfile, unsigned value, unsigned bits) /* * Put #'bits' bits of integer 'value' to the bitfile buffer 'bitfile'. * * No return value. * * Side effects: * Buffer of 'bitfile' is modified. */ { while (bits--) put_bit (bitfile, value & mask [bits]); } void close_bitfile (bitfile_t *bitfile) /* * Bitfile destructor: * Close 'bitfile', if 'bitfile->mode' == WRITE_ACCESS write bit buffer * to disk. * * No return value. * * Side effects: * Structure 'bitfile' is discarded. */ { assert (bitfile); if (bitfile->mode == WRITE_ACCESS) { unsigned bytes = fwrite (bitfile->buffer, sizeof (byte_t), BUFFER_SIZE - bitfile->bytepos, bitfile->file); if (bytes != BUFFER_SIZE - bitfile->bytepos) error ("Can't write remaining %d bytes of bitfile " "(only %d bytes written)!", BUFFER_SIZE - bitfile->bytepos, bytes); } fclose (bitfile->file); Free (bitfile->buffer); Free (bitfile->filename); Free (bitfile); } unsigned bits_processed (const bitfile_t *bitfile) /* * Return value: * Number of bits processed up to now */ { return bitfile->bits_processed; }