99 lines
1.9 KiB
C
99 lines
1.9 KiB
C
#include "retarget.h"
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#include <stdint.h>
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#include <stdio.h>
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#include "cmsis_os.h"
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#include "usbd_cdc_if.h"
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/*
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* 说明：
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* 1. 这里默认使用 FreeRTOS 的 CMSIS-RTOS2 接口
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* 2. printf 最终会走到 _write()
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* 3. _write() 内部调用 CDC_Transmit_FS() 发送到 USB 虚拟串口
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* 4. 为避免多个任务同时 printf 打花，这里提供互斥锁
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*/
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static osMutexId_t s_retarget_mutex = NULL;
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static uint8_t s_inited = 0U;
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/* 互斥锁属性 */
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static const osMutexAttr_t s_retarget_mutex_attr = {
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.name = "retargetMutex"
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};
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void Retarget_Init(void)
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{
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if (s_inited != 0U)
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{
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return;
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}
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/* 只有在内核启动后创建互斥量才有意义 */
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if (osKernelGetState() == osKernelRunning)
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{
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s_retarget_mutex = osMutexNew(&s_retarget_mutex_attr);
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}
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s_inited = 1U;
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}
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void Retarget_Lock(void)
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{
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if ((s_retarget_mutex != NULL) && (osKernelGetState() == osKernelRunning))
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{
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(void)osMutexAcquire(s_retarget_mutex, osWaitForever);
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}
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}
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void Retarget_Unlock(void)
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{
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if ((s_retarget_mutex != NULL) && (osKernelGetState() == osKernelRunning))
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{
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(void)osMutexRelease(s_retarget_mutex);
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}
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}
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/*
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* GNU 工具链 printf 重定向
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* 注意：
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* - 不要在中断里调用 printf
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* - USB CDC 忙时最多等待 20ms
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* - 等待期间 osDelay(1) 让出 CPU
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*/
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int _write(int file, char *ptr, int len)
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{
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uint32_t start_tick;
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uint8_t result;
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(void)file;
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if ((ptr == NULL) || (len <= 0))
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{
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return 0;
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}
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start_tick = HAL_GetTick();
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while (1)
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{
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result = CDC_Transmit_FS((uint8_t *)ptr, (uint16_t)len);
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if (result == USBD_OK)
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{
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return len;
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}
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/* USB 还没准备好或者正忙，最多等 20ms */
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if ((HAL_GetTick() - start_tick) > 20U)
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{
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return 0;
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}
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/* 在 FreeRTOS 下主动让出 CPU */
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if (osKernelGetState() == osKernelRunning)
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{
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osDelay(1);
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}
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}
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} |