I need a piece of standard library stm32f4 code content is to use dma and spi3 transmission data to display LCD LCD needs to open up video memory

Here is an example code for STM32F4 using DMA and SPI3 to display data on an LCD that requires access to video memory:

#include "stm32f4xx.h"

#define LCD_WIDTH 240
#define LCD_HEIGHT 320

uint16_t video_memory[LCD_WIDTH * LCD_HEIGHT];

void init_spi3(void) {
    // Enable SPI3 clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI3, ENABLE);

    // Configure GPIO pins for SPI3
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_4 | GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // Connect SPI3 pins to alternate functions
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource3, GPIO_AF_SPI3);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource4, GPIO_AF_SPI3);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource5, GPIO_AF_SPI3);

    // Configure SPI3
    SPI_InitTypeDef SPI_InitStructure;
    SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;
    SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
    SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;
    SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
    SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
    SPI_InitStructure.SPI_CRCPolynomial = 7;
    SPI_Init(SPI3, &SPI_InitStructure);

    // Enable SPI3
    SPI_Cmd(SPI3, ENABLE);
}

void init_dma2(void) {
    // Enable DMA2 clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);

    // Configure DMA2 channel 3
    DMA_InitTypeDef DMA_InitStructure;
    DMA_InitStructure.DMA_Channel = DMA_Channel_3;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(SPI3->DR);
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)video_memory;
    DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
    DMA_InitStructure.DMA_BufferSize = LCD_WIDTH * LCD_HEIGHT;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
    DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
    DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA2_Stream3, &DMA_InitStructure);

    // Enable DMA2 channel 3
    DMA_Cmd(DMA2_Stream3, ENABLE);
}

int main(void) {
    // Initialize SPI3 and DMA2
    init_spi3();
    init_dma2();

    // Wait for DMA transfer to complete
    while (DMA_GetFlagStatus(DMA2_Stream3, DMA_FLAG_TCIF3) == RESET);

    // Do something with video_memory...

    // Infinite loop
    while (1) {

    }
}

Note that this code assumes that the LCD requires access to video memory, which is stored in the video_memory array. You will need to modify this code to match the specific requirements of your LCD.