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lib: os: spsc_pbuf: Minor code cleanup

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Minor cleanup in allocation function. Using define instead of
sizeof(uint32_t) to better explain the purpose. Adding few
comments.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
This commit is contained in:
Krzysztof Chruscinski 2022-08-23 16:14:05 +02:00 committed by Fabio Baltieri
parent 716fa446cd
commit 7303ac135d
1 changed files with 20 additions and 15 deletions
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35
lib/os/spsc_pbuf.c
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@ -12,6 +12,9 @@
#include <zephyr/sys/byteorder.h>
#define LEN_SZ sizeof(uint32_t)
/* Amount of data that is left unused to distinguish between empty and full. */
#define FREE_SPACE_DISTANCE sizeof(uint32_t)
#define PADDING_MARK 0xFF
#define GET_UTILIZATION(flags) \
@ -165,26 +168,28 @@ int spsc_pbuf_alloc(struct spsc_pbuf *pb, uint16_t len, char **buf)
space = LEN_SZ + 1;
}
if (remaining >= space) {
/* Packet will fit at the end */
free_space = remaining - ((rd_idx > 0) ? 0 : sizeof(uint32_t));
if ((remaining >= space) || (rd_idx <= space)) {
/* Packet will fit at the end. Free space depends on
* presence of data at the beginning of the buffer since
* there must be one word not used to distinguish between
* empty and full state.
*/
free_space = remaining - ((rd_idx > 0) ? 0 : FREE_SPACE_DISTANCE);
} else {
if (rd_idx > space) {
/* Padding must be added. */
data_loc[wr_idx] = PADDING_MARK;
__sync_synchronize();
cache_wb(&data_loc[wr_idx], sizeof(uint8_t), flags);
/* Padding must be added. */
data_loc[wr_idx] = PADDING_MARK;
__sync_synchronize();
cache_wb(&data_loc[wr_idx], sizeof(uint8_t), flags);
wr_idx = 0;
*wr_idx_loc = wr_idx;
wr_idx = 0;
*wr_idx_loc = wr_idx;
free_space = rd_idx - sizeof(uint32_t);
} else {
free_space = remaining - (rd_idx > 0 ? 0 : sizeof(uint32_t));
}
/* Obligatory one word empty space. */
free_space = rd_idx - FREE_SPACE_DISTANCE;
}
} else {
free_space = rd_idx - wr_idx - sizeof(uint32_t);
/* Obligatory one word empty space. */
free_space = rd_idx - wr_idx - FREE_SPACE_DISTANCE;
}
len = MIN(len, MAX(free_space - (int32_t)LEN_SZ, 0));