解释：row = ((row & 0x00FF) << 8) | ((row & 0xFF00) >> 8);

+ 1) % len(grid)) if the current row is not the last row in the grid, otherwise it becomes the first row.

This code is using the modulo operator (%) to check if the current row is the last row in the grid. If it is not the last row, then it adds 1 to the row number and assigns the result to row. If it is the last row, then it assigns 0 (the first row) to row.

This code is useful when iterating through a 2-dimensional grid in a loop and you want to cycle through the rows. It ensures that the loop will continue from the first row after reaching the last row.

相关问题

编程实现：多线程操作GEC210开发板的LCD，实现BMP图片显示的“百叶窗”效果。提示：LCD映射为一片内存，多条线程分别同时操作该内存的不同区域。

这个问题需要结合具体的编程语言和开发板来实现。下面是一个C语言版本的参考代码，假设开发板的LCD映射内存为0x80000000，图片为320x240的BMP格式，要实现10个“百叶窗”效果。

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define LCD_WIDTH 320
#define LCD_HEIGHT 240
#define LCD_MEM_ADDR 0x80000000
#define WINDOW_NUM 10

typedef struct {
    int start_row;
    int end_row;
} window_t;

void* thread_func(void* arg) {
    window_t* win = (window_t*)arg;
    int row_bytes = LCD_WIDTH * 3;
    int start_addr = LCD_MEM_ADDR + win->start_row * row_bytes;
    int end_addr = LCD_MEM_ADDR + win->end_row * row_bytes;
    int i, j;
    while (1) {
        for (i = start_addr; i < end_addr; i += row_bytes) {
            for (j = i; j < i + row_bytes; j += 3) {
                *(volatile unsigned int*)j = 0xFF0000;
                *(volatile unsigned int*)(j + 1) = 0x00FF00;
                *(volatile unsigned int*)(j + 2) = 0x0000FF;
            }
        }
        usleep(10000);
    }
    return NULL;
}

int main() {
    pthread_t threads[WINDOW_NUM];
    window_t windows[WINDOW_NUM];
    int i, ret;
    for (i = 0; i < WINDOW_NUM; i++) {
        windows[i].start_row = i * (LCD_HEIGHT / WINDOW_NUM);
        windows[i].end_row = (i + 1) * (LCD_HEIGHT / WINDOW_NUM);
        ret = pthread_create(&threads[i], NULL, thread_func, &windows[i]);
        if (ret != 0) {
            perror("pthread_create");
            exit(EXIT_FAILURE);
        }
    }
    for (i = 0; i < WINDOW_NUM; i++) {
        pthread_join(threads[i], NULL);
    }
    return 0;
}

这个程序使用了pthread库来创建多个线程，每个线程都负责操作LCD映射内存的一部分，实现“百叶窗”效果。具体实现过程为：每个线程在循环中先将自己负责的区域填充为同样的颜色，然后等待一段时间再重复这个过程。由于多个线程同时操作LCD映射内存的不同区域，因此可以实现“百叶窗”效果。

请你书写代码，实现：STM32在100100处画120120正方形，背景为红色，方块为蓝色

好的，以下是代码实现：

#include "stm32f10x.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_spi.h"
#include "stm32f10x_tim.h"

void drawSquare(int x, int y, int size, int bgColor, int sqColor);

void setup()
{
    // 开启GPIO和TIM时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO | RCC_APB2Periph_TIM1, ENABLE);

    // 配置PA8为TIM1通道1的输出PWM
    GPIO_InitTypeDef gpioInit;
    gpioInit.GPIO_Pin = GPIO_Pin_8;
    gpioInit.GPIO_Mode = GPIO_Mode_AF_PP;
    gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &gpioInit);

    // 配置TIM1为PWM模式
    TIM_TimeBaseInitTypeDef timBaseInit;
    timBaseInit.TIM_Period = 7999;
    timBaseInit.TIM_Prescaler = 11;
    timBaseInit.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM1, &timBaseInit);

    TIM_OCInitTypeDef timOcInit;
    timOcInit.TIM_OCMode = TIM_OCMode_PWM1;
    timOcInit.TIM_OutputState = TIM_OutputState_Enable;
    timOcInit.TIM_Pulse = 0;
    TIM_OC1Init(TIM1, &timOcInit);
    TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);

    // 启动TIM1
    TIM_Cmd(TIM1, ENABLE);
}

int main(void)
{
    // 初始化
    setup();

    // 画正方形，默认位置和大小为(100, 100, 120)
    drawSquare(100, 100, 120, 0xff0000, 0x0000ff);

    // 死循环
    while (1);

    return 0;
}

void drawSquare(int x, int y, int size, int bgColor, int sqColor)
{
    uint16_t init_x = x;
    uint16_t init_y = y;

    // 配置SPI接口
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO | RCC_APB2Periph_GPIOA | RCC_APB2Periph_SPI1, ENABLE);

    GPIO_InitTypeDef gpio_init;
    gpio_init.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_7 | GPIO_Pin_4;
    gpio_init.GPIO_Speed = GPIO_Speed_10MHz;
    gpio_init.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &gpio_init);

    spi_init();

    // 画背景色（红色）
    set_color(bgColor);
    spi_set_pos(init_x, init_y, init_x+size-1, init_y+size-1);
    for (int i = 0; i < size*size; i++)
    {
        spi_write_data(bgColor >> 8);
        spi_write_data(bgColor & 0xff);
    }

    // 画正方形（蓝色）
    set_color(sqColor);
    spi_set_pos(init_x+1, init_y+1, init_x+size-2, init_y+size-2);
    for (int i = 0; i < (size-2)*(size-2); i++)
    {
        spi_write_data(sqColor >> 8);
        spi_write_data(sqColor & 0xff);
    }
}

void spi_init() {
    SPI_InitTypeDef spi_init;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

    spi_init.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
    spi_init.SPI_Mode = SPI_Mode_Master;
    spi_init.SPI_DataSize = SPI_DataSize_16b;
    spi_init.SPI_CPOL = SPI_CPOL_High;
    spi_init.SPI_CPHA = SPI_CPHA_2Edge;
    spi_init.SPI_NSS = SPI_NSS_Soft;
    spi_init.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
    spi_init.SPI_FirstBit = SPI_FirstBit_MSB;
    spi_init.SPI_CRCPolynomial = 7;

    SPI_Init(SPI1, &spi_init);

    SPI_Cmd(SPI1, ENABLE);
}

void set_color(uint16_t color) {
    TIM1->CCR1 = (color >> 8) << 2;
}

void spi_send_cmd(uint8_t cmd){
    GPIO_ResetBits(GPIOA, GPIO_Pin_4);
    SPI_I2S_SendData(SPI1, cmd);
    while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_BSY) != RESET);
}

void spi_send_data(uint8_t data){
    GPIO_SetBits(GPIOA, GPIO_Pin_4);
    SPI_I2S_SendData(SPI1, data);
    while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_BSY) != RESET);
}

void spi_set_pos(uint16_t x_start, uint16_t y_start, uint16_t x_end, uint16_t y_end){
    spi_send_cmd(0x2A);//Column Command Set
    spi_send_data(x_start >> 8);
    spi_send_data(x_start & 0xff);
    spi_send_data(x_end >> 8);
    spi_send_data(x_end & 0xff);

    spi_send_cmd(0x2B);//Row Command Set
    spi_send_data(y_start >> 8);
    spi_send_data(y_start & 0xff);
    spi_send_data(y_end >> 8);
    spi_send_data(y_end & 0xff);

    spi_send_cmd(0x2C);//Memory Write
}

void spi_write_data(uint16_t data) {
    spi_send_data(data >> 8);
    spi_send_data(data & 0xff);
}