streamWrite.c

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/*==================================================================*\
|                EXIP - Embeddable EXI Processor in C                |
|--------------------------------------------------------------------|
|          This work is licensed under BSD 3-Clause License          |
|  The full license terms and conditions are located in LICENSE.txt  |
\===================================================================*/

#include "streamWrite.h"
#include "ioUtil.h"

extern const unsigned char BIT_MASK[];

errorCode writeNextBit(EXIStream* strm, boolean bit_val)
{
    if(strm->buffer.bufLen <= strm->context.bufferIndx) // the whole buffer is filled! flush it!
    {
        Index numBytesWritten = 0;
        if(strm->buffer.ioStrm.readWriteToStream == NULL)
            return EXIP_BUFFER_END_REACHED;
        numBytesWritten = strm->buffer.ioStrm.readWriteToStream(strm->buffer.buf, strm->buffer.bufLen, strm->buffer.ioStrm.stream);
        if(numBytesWritten < strm->buffer.bufLen)
            return EXIP_BUFFER_END_REACHED;
        strm->context.bitPointer = 0;
        strm->context.bufferIndx = 0;
    }

    if(bit_val == FALSE)
        strm->buffer.buf[strm->context.bufferIndx] = strm->buffer.buf[strm->context.bufferIndx] & (~(1<<REVERSE_BIT_POSITION(strm->context.bitPointer)));
    else
        strm->buffer.buf[strm->context.bufferIndx] = strm->buffer.buf[strm->context.bufferIndx] | (1<<REVERSE_BIT_POSITION(strm->context.bitPointer));

    moveBitPointer(strm, 1);
    DEBUG_MSG(INFO, DEBUG_STREAM_IO, ("  @%u:%u", (unsigned int) strm->context.bufferIndx, strm->context.bitPointer));
    return EXIP_OK;
}

errorCode writeNBits(EXIStream* strm, unsigned char nbits, unsigned int bits_val)
{
    unsigned int numBitsWrite = 0; // Number of the bits written so far
    unsigned char tmp = 0;
    int bits_in_byte = 0; // Number of bits written in one iteration
    unsigned int numBytesToBeWritten = ((unsigned int) nbits) / 8 + (8 - strm->context.bitPointer < nbits % 8 );

    if(strm->buffer.bufLen <= strm->context.bufferIndx + numBytesToBeWritten)
    {
        // The buffer end is reached: there are fewer than nbits bits left in the buffer
        // Flush the buffer if possible
        errorCode tmp_err_code = EXIP_UNEXPECTED_ERROR;

        TRY(writeEncodedEXIChunk(strm));
    }

    while(numBitsWrite < nbits)
    {
        if((unsigned int)(nbits - numBitsWrite) <= (unsigned int)(8 - strm->context.bitPointer)) // The rest of the unwritten bits can be put in the current byte from the stream
            bits_in_byte = nbits - numBitsWrite;
        else // The rest of the unwritten bits are more than the bits in the current byte from the stream
            bits_in_byte = 8 - strm->context.bitPointer;

        tmp = (bits_val >> (nbits - numBitsWrite - bits_in_byte)) & BIT_MASK[bits_in_byte];
        tmp = tmp << (8 - strm->context.bitPointer - bits_in_byte);
        strm->buffer.buf[strm->context.bufferIndx] = strm->buffer.buf[strm->context.bufferIndx] & (~BIT_MASK[8 - strm->context.bitPointer]); // Initialize the unused bits with 0s
        strm->buffer.buf[strm->context.bufferIndx] = strm->buffer.buf[strm->context.bufferIndx] | tmp;

        numBitsWrite += bits_in_byte;
        moveBitPointer(strm, bits_in_byte);
    }
    DEBUG_MSG(INFO, DEBUG_STREAM_IO, ("  @%u:%u\n", (unsigned int) strm->context.bufferIndx, strm->context.bitPointer));

    return EXIP_OK;
}