sd卡读取bmp图片，以及rgb888to565, rgb888to888函数 - minichao9901/TangNano-20k-Zynq-7020 GitHub Wiki

D1 sd卡读取bmp图片存入framebuffer的函数

//从SD卡中读取BMP图片
void load_sd_bmp(u8 *frame, const char *bmp_name)
{
	static 	FATFS fatfs;
	FIL 	fil;
	u8		bmp_head[54];
	UINT 	bmp_width,bmp_height,bmp_size;
	UINT 	br;

	f_mount(&fatfs,"",1);//挂载文件系统

	f_open(&fil, bmp_name,FA_READ);	//打开文件, 注意是bmp_24bits格式
	xil_printf("open bmp\n\r");
	f_lseek(&fil,0);//移动文件读写指针到文件开头

	f_read(&fil,bmp_head,54,&br);//读取BMP文件头

	//BMP图片的分辨率和大小
	bmp_width  = *(UINT *)(bmp_head + 0x12);
	bmp_height = *(UINT *)(bmp_head + 0x16);
	bmp_size   = *(UINT *)(bmp_head + 0x22);
	xil_printf("bmp information:\n\r");
	xil_printf(" width  = %d,\n\r height = %d,\n\r size   = %d bytes \n\r",
			bmp_width,bmp_height,bmp_size);

	//读出图片，写入DDR
	f_read(&fil, frame, bmp_width*bmp_height*3,&br);
	xil_printf("br=%d\r\n", br);

	for(int i=0; i<20; i++){
		xil_printf("%x\r\n", frame[i]);
	}

	//关闭文件
	f_close(&fil);

	Xil_DCacheFlush();     //刷新Cache，将数据更新至DDR3中
	xil_printf("display bmp\n\r");
}

D2 rgb888to565函数，并截取指定区域和大小的内容

void convertRGB888toRGB565(const uint8_t *input, uint16_t *output, int inputWidth, int inputHeight, int startX, int startY, int outputWidth, int outputHeight)
{
    int i, j;

    for (i = 0; i < outputHeight; i++) {
        for (j = 0; j < outputWidth; j++) {
            // Calculate the index in the RGB888 array
            int inputIndex = ((startY + i) * inputWidth + startX + j) * 3;

            // Extract RGB888 components
            uint8_t b = input[inputIndex];
            uint8_t g = input[inputIndex + 1];
            uint8_t r = input[inputIndex + 2];

            // Convert to RGB565 format
            uint16_t rgb565 = ((r>>3) << 11) | ((g>>2) << 5) | (b>>3);

            // Store in the output array
            output[i * outputWidth + j] = rgb565;
        }
    }
}

D3 rgb888to888函数，并截取指定区域和大小的内容

void convertRGB888toRGB888(const uint8_t *input, uint8_t *output, int inputWidth, int inputHeight, int startX, int startY, int outputWidth, int outputHeight)
{
    int i, j;

    for (i = 0; i < outputHeight; i++) {
        for (j = 0; j < outputWidth; j++) {
            // Calculate the index in the RGB888 array
            int inputIndex = ((startY + i) * inputWidth + startX + j) * 3;

            // Extract RGB888 components
            uint8_t b = input[inputIndex];
            uint8_t g = input[inputIndex + 1];
            uint8_t r = input[inputIndex + 2];

            int outputIndex=(i * outputWidth + j)*3;
            // Store in the output array
            output[outputIndex] = r;
            output[outputIndex+1] = g;
            output[outputIndex+2] = b;
        }
    }
}
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