Nils O. Selåsdal
99 lines
2.4 KiB
C
99 lines
2.4 KiB
C
#ifndef UC_RINGBUG_H_
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#define UC_RINGBUG_H_
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct UCRingBuf UCRingBuf;
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struct UCRingBuf {
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char *base;
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uint32_t sz;
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uint32_t read_idx;
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uint32_t write_idx;
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};
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/**
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* Creates a new ringbuffer of at least @sz length.
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* The length will be rounded up to the neares page size
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*
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* The ringbuffer is implementd by mapping the same physical memory
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* twice into virtual memory adjacent to eachother, avoiding
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* a splitting up read/writes when the ringbuffer wraps around.
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*
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* This means accessing rb.base[rb.len] up to rb.base[rb.len * 2 - 1]
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* is accessing the same memory as rb.base[0] up to rb.base[rb.len -1]
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*
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* @param rb UCRingBuf to initialize
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* @param sz minimum length of the ring buffer
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* @returns 0 on success
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*/
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int uc_ringbuf_init(UCRingBuf *rb, uint32_t sz);
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/** Free resources used by the ring buffer.
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*
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* @return 0 on success
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*/
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int uc_ringbuf_destroy(UCRingBuf *rb);
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/**
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* Write data to the ringbuffer. The number of bytes to write must fit
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* in the free space of the ringbuffer
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*
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* @param rb UCRingBuf to write to.
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* @param data data to write
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* @param sz number of bytes to write from data
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* @return 0 on success
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*/
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int uc_ringbuf_write(UCRingBuf *rb, const void *restrict data, uint32_t sz);
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/** Read data from the ringbuffer
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*
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* @param rb UCRingBuf to write to.
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* @param data buffer to copy data into
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* @param sz number of bytes to read, must not exceed available data
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* in the buffer
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* @return 0 on success
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*/
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int uc_ringbuf_read(UCRingBuf *rb, void *restrict data, uint32_t sz);
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/** Inspect how much free space is available for writing to the ring buffer
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*
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* @param rb UCRingBuf to inspect
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* @returns number of free bytes
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*/
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uint32_t uc_ringbuf_available(const UCRingBuf *rb);
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/**
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* Length of available data in the ringbuffer
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*
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* @param rb UCRingBuf get length of
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*
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* @return length of data available to read
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*/
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static inline uint32_t uc_ringbuf_len(const UCRingBuf *rb)
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{
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return rb->write_idx - rb->read_idx;
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}
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/**
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* Get a pointer to the first unread byte
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* Caller is responsible for reading no more than the available
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* data
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*
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* @param rb UCRingBuf to peek into
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*
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* @returns pointer to first unread byte
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*/
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static inline void *uc_ringbuf_peek(const UCRingBuf *rb)
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{
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return &rb->base[rb->read_idx];
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
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