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9 years, 10 months ago.
Can a Mail Queue be altered to send different types of messages?
Can a Mail Queue be altered to send different types of messages?
Altered from RTOS Handbook Page
#include "mbed.h" #include "rtos.h" /* Mail */ typedef struct { uint32_t MessageType; /* Message type, 1 for Message from Temp Sensor and 2 for Messages from Accelerometer*/ float Temperature; /* Message Type 1 measures temperature */ } mail_MessageTypeTemperature; typedef struct { uint32_t MessageType; /* Message type, 1 for Message from Temp Sensor and 2 for Messages from Accelerometer*/ float x; /* x Axis */ float y; /* y Axis */ float z; /* z Axis */ } mail_MessageTypeAccelerometer; // Problem Line Mail<mail_t, 16> mail_box; // Problem Line void TemperatureThread(void const *argument) { while (1==1) { mail_MessageTypeTemperature *mail = mail_box.alloc(); // Allocate message space mail->MessageType = 1; // Set Message Type mail->Temperature = MeasureTemperature(); // Get Temperature and place in message mail_box.put(mail); Thread::wait(1000); } } void AccelerometerThread(void const *argument) { while (1 == 1) { mail_MessageTypeAccelerometer *mail = mail_box.alloc(); // Allocate message space mail->MessageType = 2; // Set Message Type mail->x = GetAccelerometerX(); // Get X mail->y = GetAccelerometerY(); // Get Y mail->z = GetAccelerometerZ(); // Get Z mail_box.put(mail); Thread::wait(50); } } int main(void) { Thread thread(send_thread); while (true) { osEvent evt = mail_box.get(); if (evt.status == osEventMail) { mail_t *mail = (mail_t*)evt.value.p; if (mail->MessageType == 1) { printf("\nTemperature: %.2f\n\r", mail->Temperature); } if (mail->MessageType == 2) { printf("\nTemperature: %.2f %.2f %.2f\n\r", mail->x, mail->y, mail->z); } mail_box.free(mail); } } }
1 Answer
9 years, 8 months ago.
The way to handle this is through a union type. This way the mailbox is large enough to contain the largest message. You then need to pull the values based on the MessageType received.