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Fix a cornercase problem in in the UART simulation

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This commit is contained in:
Gregory Nutt 2014-09-30 15:49:30 -06:00
parent 56574a03da
commit 16712b09fe
1 changed files with 26 additions and 19 deletions
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45
arch/sim/src/up_simuart.c
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@ -232,30 +232,37 @@ int simuart_getc(void)
int index;
int ch;
/* Locking the scheduler should eliminate the race conditions in the
* unlikely case of mutliple reading threads.
*/
sched_lock();
for (;;)
{
/* Wait for a byte to become available */
simuart_wait();
/* The UART buffer show be non-empty... check anyway */
if (g_uarthead != g_uarttail)
while (g_uarthead == g_uarttail)
{
/* Take the next byte from the tail of the buffer */
index = g_uarttail;
ch = (int)g_uartbuffer[index];
/* Increment the tai index (with wrapping) */
if (++index >= SIMUART_BUFSIZE)
{
index = 0;
}
g_uarttail = index;
return ch;
simuart_wait();
}
/* The UART buffer is non-empty... Take the next byte from the tail
* of the buffer.
*/
index = g_uarttail;
ch = (int)g_uartbuffer[index];
/* Increment the tai index (with wrapping) */
if (++index >= SIMUART_BUFSIZE)
{
index = 0;
}
g_uarttail = index;
sched_unlock();
return ch;
}
}