maple_example.ino

#include "libmaple/ring_buffer.h"
#include "streaming.h"

uint8_t buffer[32];

ring_buffer message_buffer = { buffer, 0, 0, 32 - 1 };

void queue_message(const char *str) {
  while (*str) {
    GPIOC_BASE->BRR = (1 << 13);  // time function using gpio toggle
    rb_safe_insert(&message_buffer, *str++);
    GPIOC_BASE->BSRR = (1 << 13); 
    // put a scope on PC13 to see how much time rb_safe_insert() actually takes
    // I measured ~500 nano seconds
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(PC13, OUTPUT);
  queue_message("Hello World\r\n");
}

void loop() {
  if ( !rb_is_empty(&message_buffer)) {

    Serial << "message size=" << rb_full_count(&message_buffer)
           <<     " head=" << message_buffer.head
           <<     " tail=" << message_buffer.tail
           << "\r\n";

    Serial << "[";

    do {
      int c = rb_remove(&message_buffer);
      Serial.write(c);
    } while (!rb_is_empty(&message_buffer));

    Serial << "]\r\n";

  }

  delay(1000);

  queue_message("Hello Again\r\n");
}