PNGD

// 1. Create the description of the image data processing channel. dvppChannelDesc_ is of the acldvppChannelDesc type.
dvppChannelDesc_ = acldvppCreateChannelDesc();

// 2. Create a channel for processing image data.
aclError ret = acldvppCreateChannel(dvppChannelDesc_);

// 3. Allocate input buffer (differentiated by running status).
// Call aclrtGetRunMode to obtain the run mode of the software stack. If ACL_DEVICE is returned, allocate and use the device buffer. If ACL_HOST is returned, transfer the input image data to the device by using the aclrtMemcpy call. After the data transfer is complete, the buffer needs to be freed in a timely manner.
aclrtRunMode runMode;
ret = aclrtGetRunMode(&runMode);
if(runMode == ACL_HOST){
    // Allocate the host buffer inputHostBuff and read the input image to this address. inDevBufferSize is the size of the read image.
    void* inputHostBuff = nullptr;
    inputHostBuff = malloc(inDevBufferSize);
    // Load the input image into the buffer. The ReadPicFile function is defined by the user.
    ReadPicFile(picName, inputHostBuff, inDevBufferSize);
    // Allocate the device buffer inDevBuffer_.
    ret = acldvppMalloc(&inDevBuffer_, inDevBufferSize);
    // Transfer the input image data to the device by using the aclrtMemcpy call.
    ret = aclrtMemcpy(inDevBuffer_, inDevBufferSize, inputHostBuff, inDevBufferSize, ACL_MEMCPY_HOST_TO_DEVICE);

} else {
    // Allocate input buffer inDevBuffer_ on the device.
    ret = acldvppMalloc(&inDevBuffer_, inDevBufferSize);
    // Load the input image into the buffer. The ReadPicFile function is defined by the user.
    ReadPicFile(picName, inDevBuffer_, inDevBufferSize);
}

// 4. Allocate the decoding output buffer decodeOutDevBuffer_.
// Calculate the buffer size required for the PNGD processing result.
uint32_t decodeOutBufferSize = 0;
ret = acldvppPngPredictDecSize(inputHostBuff, inDevBufferSize, PIXEL_FORMAT_RGB_888, &decodeOutBufferSize);
ret = acldvppMalloc(&decodeOutDevBuffer_, decodeOutBufferSize);
// Free the buffer in a timely manner.
free(inputHostBuff);

// 5. Create the description of the decoded image and set the attribute values.
// decodeOutputDesc is of type acldvppPicDesc.
decodeOutputDesc_ = acldvppCreatePicDesc();
acldvppSetPicDescData(decodeOutputDesc_, decodeOutDevBuffer_);
acldvppSetPicDescFormat(decodeOutputDesc_, PIXEL_FORMAT_RGB_888); 
acldvppSetPicDescSize(decodeOutputDesc_, decodeOutBufferSize);

// 6. Perform asynchronous decoding and call aclrtSynchronizeStream to block program running until all tasks in the specified stream are complete.
ret = acldvppPngDecodeAsync(dvppChannelDesc_, inDevBuffer_, inDevBufferSize, decodeOutputDesc_, stream_);
ret = aclrtSynchronizeStream(stream_);

// 7. After the decoding is complete, release the resources, including the description of the decoded output image, output buffer, channel description, and channel.
acldvppDestroyPicDesc(decodeOutputDesc_);

if(runMode == ACL_HOST){ 
    // In this mode, the processing result is on the device. Therefore, you need to call the memory copy API to transfer the result data, and then free the device buffer.
    // Allocate host buffer OutHostBuffer.
    void* OutHostBuffer = nullptr;
    OutHostBuffer = malloc(decodeOutBufferSize);
    // Transfer the processing result of the device to the host by using the aclrtMemcpy call.
    ret = aclrtMemcpy(OutHostBuffer, decodeOutBufferSize, decodeOutDevBuffer_, decodeOutBufferSize, ACL_MEMCPY_DEVICE_TO_HOST);
    // Free the input and output buffer on the device.
    (void)acldvppFree(inDevBuffer_);
    (void)acldvppFree(decodeOutDevBuffer_);
    // Free the buffer after the data is used.
    free(OutHostBuffer);
} else { 
    // The process is running on the device, and the processing result is also on the device. Free the device buffer when the data is no longer needed.
    (void)acldvppFree(inDevBuffer_);
    (void)acldvppFree(decodeOutDevBuffer_);
}
acldvppDestroyChannel(dvppChannelDesc_);
(void)acldvppDestroyChannelDesc(dvppChannelDesc_);
dvppChannelDesc_ = nullptr;

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