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https://github.com/Telecominfraproject/OpenCellular.git
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a6da62d284
Previously there was no way to remove multiple units at a time from the queue, and the queue was wasting an entry to disambiguate full from empty. There was also no way to get the free entry count from the queue, only the ability to query if it was above a required amount. The queue was also storing its constant compile time configuration as well as its dynamic state in the same structure. This wasted RAM on configuration information that doesn't change. This refactor fixes these issues, making the queue suitable for use in the new USART stream driver. Signed-off-by: Anton Staaf <robotboy@chromium.org> BRANCH=None BUG=None TEST=make buildall -j Change-Id: I284cee52d8189928dbc4c499f87ab34e14019e5a Reviewed-on: https://chromium-review.googlesource.com/210533 Reviewed-by: Vic Yang <victoryang@chromium.org> Reviewed-by: Randall Spangler <rspangler@chromium.org> Commit-Queue: Anton Staaf <robotboy@chromium.org> Tested-by: Anton Staaf <robotboy@chromium.org>
132 lines
2.8 KiB
C
132 lines
2.8 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_init(struct queue const *q)
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{
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ASSERT(POWER_OF_TWO(q->buffer_units));
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q->state->head = 0;
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q->state->tail = 0;
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}
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int queue_is_empty(struct queue const *q)
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{
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return q->state->head == q->state->tail;
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}
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size_t queue_count(struct queue const *q)
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{
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return q->state->tail - q->state->head;
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}
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size_t queue_space(struct queue const *q)
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{
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return q->buffer_units - queue_count(q);
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}
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size_t queue_add_unit(struct queue const *q, void const *src)
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{
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size_t tail = q->state->tail & (q->buffer_units - 1);
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if (queue_space(q) == 0)
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return 0;
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if (q->unit_bytes == 1)
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q->buffer[tail] = *((uint8_t *) src);
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else
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memcpy(q->buffer + tail * q->unit_bytes, src, q->unit_bytes);
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q->state->tail += 1;
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return 1;
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}
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size_t queue_add_units(struct queue const *q, void const *src, size_t count)
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{
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size_t transfer = MIN(count, queue_space(q));
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size_t tail = q->state->tail & (q->buffer_units - 1);
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size_t first = MIN(transfer, q->buffer_units - tail);
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memcpy(q->buffer + tail * q->unit_bytes,
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src,
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first * q->unit_bytes);
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if (first < transfer)
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memcpy(q->buffer,
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((uint8_t const *) src) + first * q->unit_bytes,
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(transfer - first) * q->unit_bytes);
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q->state->tail += transfer;
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return transfer;
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}
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static void queue_read_safe(struct queue const *q,
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void *dest,
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size_t head,
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size_t transfer)
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{
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size_t first = MIN(transfer, q->buffer_units - head);
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memcpy(dest,
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q->buffer + head * q->unit_bytes,
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first * q->unit_bytes);
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if (first < transfer)
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memcpy(((uint8_t *) dest) + first * q->unit_bytes,
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q->buffer,
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(transfer - first) * q->unit_bytes);
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}
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size_t queue_remove_unit(struct queue const *q, void *dest)
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{
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size_t head = q->state->head & (q->buffer_units - 1);
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if (queue_count(q) == 0)
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return 0;
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if (q->unit_bytes == 1)
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*((uint8_t *) dest) = q->buffer[head];
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else
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memcpy(dest, q->buffer + head * q->unit_bytes, q->unit_bytes);
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q->state->head += 1;
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return 1;
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}
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size_t queue_remove_units(struct queue const *q, void *dest, size_t count)
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{
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size_t transfer = MIN(count, queue_count(q));
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size_t head = q->state->head & (q->buffer_units - 1);
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queue_read_safe(q, dest, head, transfer);
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q->state->head += transfer;
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return transfer;
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}
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size_t queue_peek_units(struct queue const *q,
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void *dest,
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size_t i,
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size_t count)
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{
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size_t available = queue_count(q);
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size_t transfer = MIN(count, available - i);
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if (i < available) {
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size_t head = (q->state->head + i) & (q->buffer_units - 1);
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queue_read_safe(q, dest, head, transfer);
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}
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return transfer;
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}
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