cr50: add buffer_units_mask member into struct queue (take two)

"q->buffer_units - 1" is performed many times to wrap head and/or
tail. It should be calculated once.

BUG=None
BRANCH=cr50
TEST=None

Signed-off-by: Namyoon Woo <namyoon@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1572444
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
(cherry picked from commit 8e8dd8a8e4a0556b67f2ceed6b0fe1547989d924)

Change-Id: Ieb7dbbeb292eed2c83f5c5d06122d85ed94a65cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1644291
Tested-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Commit-Queue: Vadim Bendebury <vbendeb@chromium.org>
(cherry picked from commit 77fd02501cffcc9c0880892415b53d389b274b79)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1705712
(cherry picked from commit 88efafc7618c6575d12351469437cd2ef7cd2fe2)

2 files changed, 11 insertions, 9 deletions

diff --git a/common/queue.c b/common/queue.c
index 67934ca74e..584d0fbdfa 100644
--- a/common/queue.c
+++ b/common/queue.c
@@ -70,8 +70,8 @@ int queue_is_full(struct queue const *q)
 
 struct queue_chunk queue_get_write_chunk(struct queue const *q)
 {
-	size_t head = q->state->head & (q->buffer_units - 1);
-	size_t tail = q->state->tail & (q->buffer_units - 1);
+	size_t head = q->state->head & q->buffer_units_mask;
+	size_t tail = q->state->tail & q->buffer_units_mask;
 	size_t last = (queue_is_full(q) ? tail : /* Full           */
 		       ((tail < head) ? head :   /* Wrapped        */
 			q->buffer_units));       /* Normal | Empty */
@@ -84,8 +84,8 @@ struct queue_chunk queue_get_write_chunk(struct queue const *q)
 
 struct queue_chunk queue_get_read_chunk(struct queue const *q)
 {
-	size_t head = q->state->head & (q->buffer_units - 1);
-	size_t tail = q->state->tail & (q->buffer_units - 1);
+	size_t head = q->state->head & q->buffer_units_mask;
+	size_t tail = q->state->tail & q->buffer_units_mask;
 	size_t last = (queue_is_empty(q) ? head : /* Empty          */
 		       ((head < tail) ? tail :    /* Normal         */
 			q->buffer_units));        /* Wrapped | Full */
@@ -120,7 +120,7 @@ size_t queue_advance_tail(struct queue const *q, size_t count)
 
 size_t queue_add_unit(struct queue const *q, const void *src)
 {
-	size_t tail = q->state->tail & (q->buffer_units - 1);
+	size_t tail = q->state->tail & q->buffer_units_mask;
 
 	if (queue_space(q) == 0)
 		return 0;
@@ -146,7 +146,7 @@ size_t queue_add_memcpy(struct queue const *q,
 					size_t n))
 {
 	size_t transfer = MIN(count, queue_space(q));
-	size_t tail     = q->state->tail & (q->buffer_units - 1);
+	size_t tail     = q->state->tail & q->buffer_units_mask;
 	size_t first    = MIN(transfer, q->buffer_units - tail);
 
 	memcpy(q->buffer + tail * q->unit_bytes,
@@ -183,7 +183,7 @@ static void queue_read_safe(struct queue const *q,
 
 size_t queue_remove_unit(struct queue const *q, void *dest)
 {
-	size_t head = q->state->head & (q->buffer_units - 1);
+	size_t head = q->state->head & q->buffer_units_mask;
 
 	if (queue_count(q) == 0)
 		return 0;
@@ -209,7 +209,7 @@ size_t queue_remove_memcpy(struct queue const *q,
 					   size_t n))
 {
 	size_t transfer = MIN(count, queue_count(q));
-	size_t head     = q->state->head & (q->buffer_units - 1);
+	size_t head     = q->state->head & q->buffer_units_mask;
 
 	queue_read_safe(q, dest, head, transfer, memcpy);
 
@@ -236,7 +236,7 @@ size_t queue_peek_memcpy(struct queue const *q,
 	size_t transfer  = MIN(count, available - i);
 
 	if (i < available) {
-		size_t head = (q->state->head + i) & (q->buffer_units - 1);
+		size_t head = (q->state->head + i) & q->buffer_units_mask;
 
 		queue_read_safe(q, dest, head, transfer, memcpy);
 	}
diff --git a/include/queue.h b/include/queue.h
index ef7d001f47..2ac5c0966a 100644
--- a/include/queue.h
+++ b/include/queue.h
@@ -75,6 +75,7 @@ struct queue {
 	struct queue_policy const *policy;
 
 	size_t  buffer_units; /* size of buffer (in units) */
+	size_t  buffer_units_mask; /* size of buffer (in units) - 1*/
 	size_t  unit_bytes;   /* size of unit   (in byte) */
 	uint8_t *buffer;
 };
@@ -89,6 +90,7 @@ struct queue {
 		.state        = &((struct queue_state){}),	\
 		.policy       = &POLICY,			\
 		.buffer_units = SIZE,				\
+		.buffer_units_mask = SIZE - 1,			\
 		.unit_bytes   = sizeof(TYPE),			\
 		.buffer       = (uint8_t *) &((TYPE[SIZE]){}),	\
 	})