bmpi_32bit_decoder.c

bmp图像文件解码器的arm版本的源代码

/*

*******************************************************************************
*
* FILE NAME:            
*   bmp_32bit_decoder.c
*
* DESCRIPTION:
*   source code for BMP decoder with 32-bit.
*
* MODULE: 
*   BMP (BitMaP) decoder.
* 

*  
*******************************************************************************
*/

/*
*******************************************************************************
* Include files
*******************************************************************************
*/

/* -- Include for BMP ressources -- */
#include "bmp_decoder_api.h"
#include "bmpi_decoder.h"

/*
*******************************************************************************
* 
* FUNCTION NAME:
*   BMPI_Decode32Bits()
*
* FUNCTION DESCRIPTION:
*   This function decodes a BMP image with 16-bit color.
*
* INPUTS:
*   pu8InputBuffer  : pointer to input buffer
*   pu8Mask         : pointer to color mask in palette
*   sImageInfo      : image information structure 
*   func            : pointer to callback function
*
* OUTPUTS:
*   psOutputBuffer  : pointer to output buffer (structure)
*   
* RETURN:
*   '0' if successful or '1' if failed.
*
* GLOBALS ACCESSED/MODIFIED:
*   < List all global variables this function accesses and/or modifies >
*
* SPECIAL NOTES:
*
*******************************************************************************
*/
OP_UINT8 BMPI_Decode32Bits
(
    OP_UINT8                     *pu8InputBuffer,
    OP_UINT8                     *pu8Mask,
    BMP_IMAGE_INFO               sImageInfo,
    OP_BOOLEAN                   func(OP_UINT16 x, OP_UINT16 y),
    IMAGE_DECODER_OUTPUT_TYPE    *psOutputBuffer)
{


    /*-----------------------------------------------------------------------*/
    /* DECLARE LOCAL VARIABLES                                                 */
    /*-----------------------------------------------------------------------*/

    OP_UINT16   u8RedMask;                           /* mask for red color */
    OP_UINT16   u8GreenMask;                         /* mask for green color */
    OP_UINT16   u8BlueMask;                          /* mask for blue color */
    OP_UINT32   u32XinvCnt;                          /* inverse counter on X-axis */
    OP_UINT32   u32YinvCnt;                          /* inverse counter on Y-axis */
    OP_UINT32   u32Temp;                             /* 32-bit temporary variable */


    /*-----------------------------------------------------------------------*/
    /* DECODE 32-BIT COLORS                                                   */
    /*-----------------------------------------------------------------------*/

    /* determine bit masks for each color plane */
    if(sImageInfo.u32Compression == BI_RGB)                /* no bit masking */
    {
        u8RedMask   = 0xff;
        u8GreenMask = 0xff;
        u8BlueMask  = 0xff;
    }
    else                                        /* with specific bit masking */
    {
        u32Temp = BMPI_ReadLittleEndianU32(pu8Mask);
        pu8Mask+=4;
        u8RedMask = BMPI_RetrieveBitMask32Bits(u32Temp);
        u32Temp = BMPI_ReadLittleEndianU32(pu8Mask);
        pu8Mask+=4;
        u8GreenMask = BMPI_RetrieveBitMask32Bits(u32Temp);
        u32Temp = BMPI_ReadLittleEndianU32(pu8Mask);
        u8BlueMask = BMPI_RetrieveBitMask32Bits(u32Temp);
    }

    /* -- Extract data in bitmap pixel by pixel -- */
    /* vertical loop */
    u32YinvCnt = sImageInfo.u32ImageHeight;
    while(u32YinvCnt--)
    {

        /* horizontal loop */
        u32XinvCnt = sImageInfo.u32ImageWidth;
        while(u32XinvCnt--)                      
        {
            psOutputBuffer->u8Blue  = (*pu8InputBuffer++) & u8BlueMask;
            psOutputBuffer->u8Green = (*pu8InputBuffer++) & u8GreenMask;
            psOutputBuffer->u8Red   = (*pu8InputBuffer++) & u8RedMask;
            pu8InputBuffer++;                 /* every 4th bytes are ignored */
            psOutputBuffer->u8Alpha = 0xff;      /* set to opaque as default */
            psOutputBuffer++;                  /* move pointer to next pixel */
        }

    }


    /*-----------------------------------------------------------------------*/
    /* DECODED SUCCESSFULLY                                                  */
    /*-----------------------------------------------------------------------*/

    return(0);
}



/*
*******************************************************************************
* 
* FUNCTION NAME:
*   BMPI_RetrieveBitMask32Bits()
*
* FUNCTION DESCRIPTION:
*   This function retrieves the bit mask of one color from a 32-bit data
*   in palette.
*
* INPUTS:
*   u32BitField : bit field from palette where mask is included. 
*
* OUTPUTS:
*   None.
*   
* RETURN:
*   u8Mask : bit mask for one color.
*
* GLOBALS ACCESSED/MODIFIED:
*   < List all global variables this function accesses and/or modifies >
*
* SPECIAL NOTES:
*
*******************************************************************************
*/
OP_UINT8 BMPI_RetrieveBitMask32Bits
(
    OP_UINT32   u32BitField
)
{
    /*-----------------------------------------------------------------------*/
    /* INITIALIZE RETURNED PARAMETERS                                          */
    /*-----------------------------------------------------------------------*/

    OP_UINT8    u8Mask;
    OP_UINT32   u32LoopCounter;                      /* loop counter */
    OP_UINT32   u32Temp;                             /* 32-bit temporary variable */

    /*-----------------------------------------------------------------------*/
    /* DETERMINE 8-bit MASK                                                   */
    /*-----------------------------------------------------------------------*/

    u32LoopCounter = 0;
    u32Temp = u32BitField & 0x00000001;
    while( (!u32Temp) && (u32LoopCounter < 32) )
    {
        u32BitField = (u32BitField >> 1) & 0x7fffffff;
        u32Temp = u32BitField & 0x00000001;
        u32LoopCounter++;
    }
    if(u32LoopCounter != 32)
    {
        u8Mask = (OP_UINT8)u32BitField;
    }
    else
    {
        u8Mask = 0x00;
    }

    return(u8Mask);

}