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sys/tsrb: Make thread-safe

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Drop the requirement of having only one writer and one reader, as the name of
the ring-buffer does not indicate any limitation on the thread-safety. The
two-threads-one-buffer kind of ring buffer can be reintroduced with a different
name.
This commit is contained in:
Marian Buschsieweke 2020-10-13 10:32:41 +02:00
parent 2df92b0d61
commit 0d0b14de29
No known key found for this signature in database
GPG Key ID: 61F64C6599B1539F
2 changed files with 37 additions and 17 deletions
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29
sys/include/tsrb.h
View File

@ -12,9 +12,6 @@
* @brief Thread-safe ringbuffer implementation
* @{
*
* @note This ringbuffer implementation can be used without locking if
* there's only one producer and one consumer.
*
* @attention Buffer size must be a power of two!
*
* @file
@ -30,6 +27,8 @@
#include <stddef.h>
#include <stdint.h>
#include "irq.h"
#ifdef __cplusplus
extern "C" {
#endif
@ -40,8 +39,8 @@ extern "C" {
typedef struct tsrb {
uint8_t *buf; /**< Buffer to operate on. */
unsigned int size; /**< Size of buffer, must be power of 2. */
volatile unsigned reads; /**< total number of reads */
volatile unsigned writes; /**< total number of writes */
unsigned reads; /**< total number of reads */
unsigned writes; /**< total number of writes */
} tsrb_t;
/**
@ -76,7 +75,10 @@ static inline void tsrb_init(tsrb_t *rb, uint8_t *buffer, unsigned bufsize)
*/
static inline int tsrb_empty(const tsrb_t *rb)
{
return (rb->reads == rb->writes);
unsigned irq_state = irq_disable();
int retval = (rb->reads == rb->writes);
irq_restore(irq_state);
return retval;
}
@ -87,7 +89,10 @@ static inline int tsrb_empty(const tsrb_t *rb)
*/
static inline unsigned int tsrb_avail(const tsrb_t *rb)
{
return (rb->writes - rb->reads);
unsigned irq_state = irq_disable();
int retval = (rb->writes - rb->reads);
irq_restore(irq_state);
return retval;
}
/**
@ -98,7 +103,10 @@ static inline unsigned int tsrb_avail(const tsrb_t *rb)
*/
static inline int tsrb_full(const tsrb_t *rb)
{
return (rb->writes - rb->reads) == rb->size;
unsigned irq_state = irq_disable();
int retval = (rb->writes - rb->reads) == rb->size;
irq_restore(irq_state);
return retval;
}
/**
@ -108,7 +116,10 @@ static inline int tsrb_full(const tsrb_t *rb)
*/
static inline unsigned int tsrb_free(const tsrb_t *rb)
{
return (rb->size - rb->writes + rb->reads);
unsigned irq_state = irq_disable();
int retval = (rb->size - rb->writes + rb->reads);
irq_restore(irq_state);
return retval;
}
/**

25
sys/tsrb/tsrb.c
View File

@ -17,6 +17,7 @@
* @}
*/
#include "irq.h"
#include "tsrb.h"
static void _push(tsrb_t *rb, uint8_t c)
@ -31,51 +32,59 @@ static uint8_t _pop(tsrb_t *rb)
int tsrb_get_one(tsrb_t *rb)
{
int retval = -1;
unsigned irq_state = irq_disable();
if (!tsrb_empty(rb)) {
return _pop(rb);
}
else {
return -1;
retval = _pop(rb);
}
irq_restore(irq_state);
return retval;
}
int tsrb_get(tsrb_t *rb, uint8_t *dst, size_t n)
{
size_t tmp = n;
unsigned irq_state = irq_disable();
while (tmp && !tsrb_empty(rb)) {
*dst++ = _pop(rb);
tmp--;
}
irq_restore(irq_state);
return (n - tmp);
}
int tsrb_drop(tsrb_t *rb, size_t n)
{
size_t tmp = n;
unsigned irq_state = irq_disable();
while (tmp && !tsrb_empty(rb)) {
_pop(rb);
tmp--;
}
irq_restore(irq_state);
return (n - tmp);
}
int tsrb_add_one(tsrb_t *rb, uint8_t c)
{
int retval = -1;
unsigned irq_state = irq_disable();
if (!tsrb_full(rb)) {
_push(rb, c);
return 0;
}
else {
return -1;
retval = 0;
}
irq_restore(irq_state);
return retval;
}
int tsrb_add(tsrb_t *rb, const uint8_t *src, size_t n)
{
size_t tmp = n;
unsigned irq_state = irq_disable();
while (tmp && !tsrb_full(rb)) {
_push(rb, *src++);
tmp--;
}
irq_restore(irq_state);
return (n - tmp);
}