forked from PAWPAW-Mirror/lib_xua
a695e58524
Since the functions are simple make them inline functions. This provides a small code size saving.
55 lines
1.1 KiB
C
55 lines
1.1 KiB
C
#ifndef QUEUE_H_
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#define QUEUE_H_
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#include <xassert.h>
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typedef struct queue_t {
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/// Read index.
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unsigned rdptr;
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/// Write index.
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unsigned wrptr;
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unsigned size;
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unsigned mask;
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} queue_t;
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inline int is_power_of_2(unsigned x) {
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return x != 0 && (x & (x - 1)) == 0;
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}
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inline void queue_init(queue_t &q, unsigned size) {
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assert(is_power_of_2(size));
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q.rdptr = 0;
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q.wrptr = 0;
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q.size = size;
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q.mask = size - 1; // Assumes power of two.
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}
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inline int queue_is_empty(const queue_t &q) {
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return q.wrptr == q.rdptr;
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}
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inline int queue_is_full(const queue_t &q) {
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return q.wrptr - q.rdptr == q.size;
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}
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inline void queue_push_word(queue_t &q, unsigned array[], unsigned data)
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{
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assert(!queue_is_full(q));
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array[q.wrptr++ & q.mask] = data;
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}
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inline unsigned queue_pop_word(queue_t &q, unsigned array[]) {
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assert(!queue_is_empty(q));
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return array[q.rdptr++ & q.mask];
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}
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inline unsigned queue_items(const queue_t &q) {
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return q.wrptr - q.rdptr;
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}
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inline unsigned queue_space(const queue_t &q) {
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return q.size - queue_items(q);
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}
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#endif /* QUEUE_H_ */
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