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sys: newlib: use double-lock scheme for uart ringbuffer #3111

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Jun 1, 2015
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sys: newlib: use double-lock scheme for uart ringbuffer #3111

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23 changes: 11 additions & 12 deletions sys/newlib/syscalls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ caddr_t heap_top = (caddr_t)&_sheap + 4;
/**
* @brief use mutex for waiting on incoming UART chars
*/
static mutex_t uart_rx_mutex;
static mutex_t uart_rx_mutex = MUTEX_INIT;
static char rx_buf_mem[STDIO_RX_BUFSIZE];
static ringbuffer_t rx_buf;
#endif
Expand All @@ -65,16 +65,14 @@ static ringbuffer_t rx_buf;
void rx_cb(void *arg, char data)
{
(void)arg;

#ifdef MODULE_UART0
#ifndef MODULE_UART0
ringbuffer_add_one(&rx_buf, data);
mutex_unlock(&uart_rx_mutex);
#else
if (uart0_handler_pid) {
uart0_handle_incoming(data);

uart0_notify_thread();
}
#else
ringbuffer_add_one(&rx_buf, data);
mutex_unlock(&uart_rx_mutex);
#endif
}

Expand All @@ -84,7 +82,7 @@ void rx_cb(void *arg, char data)
void _init(void)
{
#ifndef MODULE_UART0
mutex_init(&uart_rx_mutex);
mutex_lock(&uart_rx_mutex);
ringbuffer_init(&rx_buf, rx_buf_mem, STDIO_RX_BUFSIZE);
#endif
uart_init(STDIO, STDIO_BAUDRATE, rx_cb, 0, 0);
Expand Down Expand Up @@ -205,10 +203,11 @@ int _open_r(struct _reent *r, const char *name, int mode)
int _read_r(struct _reent *r, int fd, void *buffer, unsigned int count)
{
#ifndef MODULE_UART0
while (rx_buf.avail == 0) {
mutex_lock(&uart_rx_mutex);
}
return ringbuffer_get(&rx_buf, (char*)buffer, rx_buf.avail);
mutex_lock(&uart_rx_mutex);

count = count < rx_buf.avail ? count : rx_buf.avail;

return ringbuffer_get(&rx_buf, (char*)buffer, count);
#else
char *res = (char*)buffer;
res[0] = (char)uart0_readc();
Expand Down