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https://github.com/Telecominfraproject/OpenCellular.git
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a9541220dc
For simplicity of the code, we don't allow (head == tail) when the queue is full. But currently we are wasting the size of a single unit, while we can actually just waste 1 byte. Let's fix this. BUG=None TEST=Pass the unit test. BRANCH=None Change-Id: Id09c20a9345ebb3ec0cad659afe36e25b422e688 Signed-off-by: Vic Yang <victoryang@chromium.org> Reviewed-on: https://gerrit.chromium.org/gerrit/58058 Reviewed-by: Yung-Chieh Lo <yjlou@chromium.org>
58 lines
1.2 KiB
C
58 lines
1.2 KiB
C
/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Queue data structure implementation.
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*/
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#include "queue.h"
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#include "util.h"
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void queue_reset(struct queue *queue)
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{
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queue->head = queue->tail = 0;
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}
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int queue_is_empty(const struct queue *q)
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{
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return q->head == q->tail;
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}
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int queue_has_space(const struct queue *q, int unit_count)
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{
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if (q->tail >= q->head)
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return (q->tail + unit_count * q->unit_bytes) <=
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(q->head + q->buf_bytes - 1);
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else
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return (q->tail + unit_count * q->unit_bytes) <=
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(q->head - 1);
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}
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void queue_add_units(struct queue *q, const void *src, int unit_count)
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{
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const uint8_t *s = (const uint8_t *)src;
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if (!queue_has_space(q, unit_count))
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return;
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for (unit_count *= q->unit_bytes; unit_count; unit_count--) {
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q->buf[q->tail++] = *(s++);
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q->tail %= q->buf_bytes;
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}
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}
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int queue_remove_unit(struct queue *q, void *dest)
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{
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int count;
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uint8_t *d = (uint8_t *)dest;
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if (queue_is_empty(q))
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return 0;
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for (count = q->unit_bytes; count; count--) {
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*(d++) = q->buf[q->head++];
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q->head %= q->buf_bytes;
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}
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return 1;
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}
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