STM32 USB Host Library 学习笔记 (1) USB

1 /** 2 * @brief USB_OTG_ReadPacket : Reads a packet from the Rx FIFO 3 * @param pdev : Selected device 4 * @param dest : Destination Pointer 5 * @param bytes : No. of bytes 6 * @retval None 7 */ 8 void *USB_OTG_ReadPacket(USB_OTG_CORE_HANDLE *pdev, 9 uint8_t *dest, 10 uint16_t len) 11 { 12 uint32_t i=0; 13 //uint32_t count32b = (len + 3) / 4; 14 uint32_t count32b = (len) / 4; 15 uint32_t count8b = (len) & 3; 16 17 __IO uint32_t *fifo = pdev->regs.DFIFO[0]; 18 19 for ( i = 0; i < count32b; i++, dest += 4 ) 20 { 21 *(__packed uint32_t *)dest = USB_OTG_READ_REG32(fifo); 22 23 } 24 25 if ( count8b ) 26 { 27 count32b = USB_OTG_READ_REG32(fifo); 28 while ( count8b > 0 ) 29 { 30 *dest = count32b; 31 count32b >>= 8; 32 dest++; 33 count8b--; 34 } 35 }36 return ((void *)dest); 37 }

/** @file stm32f4xx_ll_usb.c  * @author MCD Application Team  * @version V1.1.0  * @date 19-June-2014  * @brief USB Low Layer HAL module driver.  */

/** * @brief USB_ReadPacket : read a packet from the Tx FIFO associated * with the EP/channel * @param USBx : Selected device * @param src : source pointer * @param ch_ep_num : endpoint or host channel number * @param len : Noumber of bytes to read * @param dma: USB dma enabled or disabled * This parameter can be one of the these values: * 0 : DMA feature not used * 1 : DMA feature used * @retval pointer to desctination buffer */ void *USB_ReadPacket(USB_OTG_GlobalTypeDef *USBx, uint8_t *dest, uint16_t len) { uint32_t i=0; uint32_t count32b = (len + 3) / 4; for ( i = 0; i < count32b; i++, dest += 4 ) { *(__packed uint32_t *)dest = USBx_DFIFO(0); // dest buffer overflow if (len != n*4) } return ((void *)dest); }

 

转载于:https://www.cnblogs.com/shangdawei/archive/2012/09/01/2667125.html

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