_RINGBUF Struct Reference
[USART Driver Frame, USART Driver Frame]

#include <dev/usart.h>

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Detailed Description

Character device ring buffer structure.

Data Fields
u_char *volatile	rbf_head
	Buffer head pointer.
u_char *volatile	rbf_tail
	Buffer tail pointer.
u_char *	rbf_start
	First buffer address.
u_char *	rbf_last
	Last buffer address.
size_t	rbf_siz
	Total buffer size.
volatile size_t	rbf_cnt
	Number of bytes in the buffer.
size_t	rbf_lwm
	Buffer low watermark.
size_t	rbf_hwm
	Buffer high watermark.
HANDLE	rbf_que
	Queue of waiting threads.

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Field Documentation

u_char* volatile _RINGBUF::rbf_head

Buffer head pointer. Changed by the receiver interrupt.

u_char* volatile _RINGBUF::rbf_tail

Buffer tail pointer. Changed by the transmitter interrupt.

size_t _RINGBUF::rbf_siz

Total buffer size. Zero, if no buffer available.

volatile size_t _RINGBUF::rbf_cnt

Number of bytes in the buffer. Changed by receiver and transmitter interrupts.

size_t _RINGBUF::rbf_lwm

Buffer low watermark. If the number of bytes in the buffer reaches this value, then the previously disabled buffer input is enabled again.

size_t _RINGBUF::rbf_hwm

Buffer high watermark. If the number of bytes in the buffer reaches this value, then buffer input is disabled.

HANDLE _RINGBUF::rbf_que

Queue of waiting threads. Consuming threads are added to this queue when the buffer is empty. Producing threads are added to this queue when the buffer is full.

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