tools/dtdesc/c_iff/readchunkdata.c

   1 /*
   2  *  c_iff - a portable IFF-parser
   3  *
   4  *  Copyright (C) 2000, 2001 Joerg Dietrich
   5  *
   6  *  This is the AROS-version of c_iff.
   7  *  It is distributed under the AROS Public License.
   8  *  But I reserve the right to distribute
   9  *  my own version under other licenses.
  10  */
  11
  12 /*
  13  *  readchunkdata.c - read the data of the actual chunk
  14  */
  15
  16 #include "c_iff.h"
  17
  18 /****** c_iff/ReadChunkData *************************************************
  19 *
  20 *   NAME
  21 *       ReadChunkData -- Read some data from the current chunk
  22 *
  23 *   SYNOPSIS
  24 *       Size = ReadChunkData( TheHandle,Buffer,BufferSize )
  25 *
  26 *       long ReadChunkData( struct IFFHandle *,char *,size_t )
  27 *
  28 *   FUNCTION
  29 *       Reads some data from the current chunk into Buffer.
  30 *       If BufferSize is greater than the chunksize, the whole chunk
  31 *       is copied into the Buffer otherwise BufferSize bytes are copied.
  32 *
  33 *   INPUTS
  34 *       TheHandle   - IFFHandle to read from
  35 *       Buffer      - the buffer to write to
  36 *       BufferSize  - size of the provided buffer
  37 *
  38 *   RESULT
  39 *       Size        - number of bytes copied to the buffer
  40 *                     Can be 0 when no bytes are copied,
  41 *                     or -1 when an error occured.
  42 *
  43 *   EXAMPLE
  44 *
  45 *   NOTES
  46 *       To read data from a chunk you have to start this chunk with
  47 *       ReadChunkHeader() .
  48 *       Make sure to read or skip the entire chunk!
  49 *
  50 *   BUGS
  51 *
  52 *   SEE ALSO
  53 *       ReadChunkHeader() SkipChunkData()
  54 *
  55 *****************************************************************************
  56 *
  57 *       Private notes:
  58 */
  59
  60 long ReadChunkData(struct IFFHandle *TheHandle,
  61                    char *Buffer,
  62                    size_t BufferSize)
  63 {
  64  long Ret;
  65  size_t BytesToRead;
  66
  67  if(!(TheHandle && Buffer && (BufferSize>0)))
  68  {
  69   return(-1);
  70  }
  71
  72  BytesToRead=(BufferSize>TheHandle->BytesLeftInChunk)?TheHandle->BytesLeftInChunk:BufferSize;
  73
  74  Ret=fread(Buffer, 1, BytesToRead, TheHandle->TheFile);
  75
  76  TheHandle->BytesLeftInChunk-=Ret;
  77
  78  if(TheHandle->BytesLeftInChunk==0)
  79  {
  80   TheHandle->ChunkID=INVALID_ID;
  81  }
  82
  83  return(Ret);
  84 }
  85
  86