Blend

This sample demonstrates the alpha blend function of the PPE peripheral.

Requirements

The sample supports the following development kits:

Development Kit
Hardware Platforms	Board Name
RTL87x2G HDK	RTL87x2G EVB

For more requirements, please refer to Quick Start

Wiring

None

Building and Downloading

This sample can be found in the SDK folder:

Keil

Project file: samples\peripheral\ppe\blend\proj\rtl87x2g\mdk

GCC

Project file: samples\peripheral\ppe\blend\proj\rtl87x2g\gcc

To build and run the sample, follow the steps listed below:

Open Sample Project File.
To build the target, follow the steps listed on the Generating App Image in Quick Start.
After a successful compilation, the app bin app_MP_xxx.bin will be generated in the directory mdk\bin.
To download app bin into EVB board, follow the steps listed on the MP Tool Download in Quick Start.
Press reset button on EVB board and it will start running.

Experimental Verification

After the sample is executed, observing the following log in the DebugAnalyzer window indicates successful blending:

PPE blend test passed 0

Code Overview

This chapter will be introduced according to the following several parts：

Source code directory.
Peripheral initialization will be introduced in chapter Initialization.
Functional implementation after initialization will be introduced in chapter Functional implementation.

Source Code Directory

Project directory: sdk\samples\peripheral\ppe\blend\proj
Source code directory: sdk\samples\peripheral\ppe\blend\src

Source files are currently categorized into several groups as below.

└── Project: decompress
    └── ppe
        ├── config                   includes project construct configuration
        ├── display                  includes the peripheral drivers related with display
        └── Device                   includes startup code
            ├── startup_rtl.c
            └── system_rtl.c
        ├── CMSIS                    includes CMSIS header files
        ├── CMSE Library             non-secure callable lib
        ├── lib                      includes all binary symbol files that user application is built on
        ├── peripheral               includes all peripheral drivers and module code used by the application
        └── APP                      source code of PPE blend sample
            ├── main_ns.c
            └── ppe_test.c

Initialization

The initialization process is included in PPE_test().

Initialize data of foreground buffer and background buffer.
Initialize PPE structures that contain information of foreground and background.

source.address = (uint32_t) source_buffer;
source.memory = source_buffer;
source.color_key_en = DISABLE;
source.color_key_value = 0;
source.format = PPE_ABGR8888;
source.width = 64;
source.height = 64;

target.address = (uint32_t) target_buffer;
target.memory = target_buffer;
target.color_key_en = DISABLE;
target.color_key_value = 0;
target.format = PPE_ABGR8888;
target.width = 64;
target.height = 64;

After determining translation of foreground, invoke PPE_blend() to start to blend.

ppe_translate_t trans = {.x = 0, .y = 0};
PPE_ERR err = PPE_blend(&source, &target, &trans, PPE_SRC_OVER_MODE);

Tip

About correctness of blending result, refer to Troubleshooting.

Functional Implementation

While running PPE_blend(), foreground will be blended to background from translated position. When this function has finished executing, it indicates PPE has also finished its work to blend.

Troubleshooting

Correctness Check

After PPE_blend() has been finished, the output buffer will be compared with golden data. If any error occurs, the following log will be displayed in DebugAnalyzer Tool:

PPE alpha blend error

And also the error code will be printed at the last line with the following log:

PPE blend test passed ‘error code’