buffer.c File Reference

iSensor-SPI-Buffer buffer implementation More...

#include "reg.h"
#include "buffer.h"
#include "stm32f3xx_hal.h"

Include dependency graph for buffer.c:

Functions
static uint8_t buf[BUF_SIZE]	__attribute__ ((aligned(32)))
uint32_t	Buffer_Can_Add_Element ()
	Checks if an element can be added to the buffer. More...
uint8_t *	Buffer_Take_Element ()
	Take a single element from the buffer. More...
uint8_t *	Buffer_Add_Element ()
	Add an element to the buffer. More...
void	Buffer_Reset ()
	Clears the buffer data structure. More...

Variables
uint32_t	g_bufLastRegIndex
uint32_t	g_bufCount = 0
uint32_t	g_bufNumWords32
static volatile uint32_t	buf_head = 0
static volatile uint32_t	buf_tail = 0
static uint32_t	buf_increment = 64
static uint32_t	buf_replaceOldest = 0
static uint32_t	buf_maxCount
static uint32_t	buf_lastEntryIndex

Detailed Description

iSensor-SPI-Buffer buffer implementation

Copyright (c) Analog Devices Inc, 2020 All Rights Reserved.

Date

3/19/2020

Author

A. Nolan (alex..nosp@m.nola.nosp@m.n@ana.nosp@m.log..nosp@m.com)

Function Documentation

__attribute__()

static uint8_t buf [BUF_SIZE] __attribute__ ( (aligned(32))  )

static

The buffer storage (aligned to allow word-wise retrieval of buffer data)

Buffer_Add_Element()

uint8_t* Buffer_Add_Element

(

)

Add an element to the buffer.

Returns

Pointer to the new element added to the buffer

New elements always get added to the head of the buffer, in both buffer modes. If the buffer is full and ReplaceOldest is set to true, then the head continues moving through the buffer memory. If replace oldest is set to false, the head stays still when the buffer data structure reaches capacity.

Buffer_Can_Add_Element()

uint32_t Buffer_Can_Add_Element

(

)

Checks if an element can be added to the buffer.

Returns

0 if no element can be added to the buffer, 1 otherwise

The return value depends on the replace oldest setting and buffer count

Buffer_Reset()

void Buffer_Reset

(

)

Clears the buffer data structure.

Returns

void

This function resets the buffer to its default state. All stored buffer entries are discarded. The buffer control registers (buffer length, buffer config) are both validated to ensure the buffer is initialized to a valid state.

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Buffer_Take_Element()

uint8_t* Buffer_Take_Element

(

)

Take a single element from the buffer.

Returns

Pointer to the element retrieved from the buffer

In FIFO mode (queue) this function takes from the tail and moves the tail pointer down. This function is called from the main loop when a buffer dequeue is requested. As such, the ISRs are disabled for the duration of this function execution to prevent issues with g_bufCount being inadvertently changed

Variable Documentation

buf_head

volatile uint32_t buf_head = 0

static

Index within buffer array for buffer head

buf_increment

uint32_t buf_increment = 64

static

Increment per buffer entry. This is buffer length + 4, padded to multiple of 4

buf_lastEntryIndex

uint32_t buf_lastEntryIndex

static

Position at which buffer needs to wrap around

buf_maxCount

uint32_t buf_maxCount

static

Buffer max count (determined once when buffer is initialized)

buf_replaceOldest

uint32_t buf_replaceOldest = 0

static

Buffer full setting (0 -> stop adding, Not 0 -> replace oldest)

buf_tail

volatile uint32_t buf_tail = 0

static

Index within buffer array for buffer tail

g_bufCount

uint32_t g_bufCount = 0

Number of elements currently stored in the buffer. Global scope

g_bufLastRegIndex

uint32_t g_bufLastRegIndex

Index for the last buffer output register. This is based on buffer size. Global scope

g_bufNumWords32

uint32_t g_bufNumWords32

Number of 32-bit words per buffer entry. Global scope