From 4ba8614c006f9828f0796c140bc3e13c9e67938c Mon Sep 17 00:00:00 2001 From: Yuval Adam Date: Mon, 29 Oct 2012 23:06:01 +0200 Subject: Added utils --- utils/ringbuf.c | 709 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 709 insertions(+) create mode 100644 utils/ringbuf.c (limited to 'utils/ringbuf.c') diff --git a/utils/ringbuf.c b/utils/ringbuf.c new file mode 100644 index 0000000..ff49f9e --- /dev/null +++ b/utils/ringbuf.c @@ -0,0 +1,709 @@ +//***************************************************************************** +// +// ringbuf.c - Ring buffer management utilities. +// +// Copyright (c) 2008-2012 Texas Instruments Incorporated. All rights reserved. +// Software License Agreement +// +// Texas Instruments (TI) is supplying this software for use solely and +// exclusively on TI's microcontroller products. The software is owned by +// TI and/or its suppliers, and is protected under applicable copyright +// laws. You may not combine this software with "viral" open-source +// software in order to form a larger program. +// +// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS. +// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT +// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY +// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL +// DAMAGES, FOR ANY REASON WHATSOEVER. +// +// This is part of revision 9453 of the Stellaris Firmware Development Package. +// +//***************************************************************************** + +#include "inc/hw_types.h" +#include "driverlib/debug.h" +#include "driverlib/interrupt.h" +#include "utils/ringbuf.h" + +//***************************************************************************** +// +//! \addtogroup ringbuf_api +//! @{ +// +//***************************************************************************** + +//***************************************************************************** +// +// Define NULL, if not already defined. +// +//***************************************************************************** +#ifndef NULL +#define NULL ((void *)0) +#endif + +//***************************************************************************** +// +// Change the value of a variable atomically. +// +// \param pulVal points to the index whose value is to be modified. +// \param ulDelta is the number of bytes to increment the index by. +// \param ulSize is the size of the buffer the index refers to. +// +// This function is used to increment a read or write buffer index that may be +// written in various different contexts. It ensures that the read/modify/write +// sequence is not interrupted and, hence, guards against corruption of the +// variable. The new value is adjusted for buffer wrap. +// +// \return None. +// +//***************************************************************************** +static void +UpdateIndexAtomic(volatile unsigned long *pulVal, unsigned long ulDelta, + unsigned long ulSize) +{ + tBoolean bIntsOff; + + // + // Turn interrupts off temporarily. + // + bIntsOff = IntMasterDisable(); + + // + // Update the variable value. + // + *pulVal += ulDelta; + + // + // Correct for wrap. We use a loop here since we don't want to use a + // modulus operation with interrupts off but we don't want to fail in + // case ulDelta is greater than ulSize (which is extremely unlikely but...) + // + while(*pulVal >= ulSize) + { + *pulVal -= ulSize; + } + + // + // Restore the interrupt state + // + if(!bIntsOff) + { + IntMasterEnable(); + } +} + +//***************************************************************************** +// +//! Determines whether the ring buffer whose pointers and size are provided +//! is full or not. +//! +//! \param ptRingBuf is the ring buffer object to empty. +//! +//! This function is used to determine whether or not a given ring buffer is +//! full. The structure is specifically to ensure that we do not see +//! warnings from the compiler related to the order of volatile accesses +//! being undefined. +//! +//! \return Returns \b true if the buffer is full or \b false otherwise. +// +//***************************************************************************** +tBoolean +RingBufFull(tRingBufObject *ptRingBuf) +{ + unsigned long ulWrite; + unsigned long ulRead; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Copy the Read/Write indices for calculation. + // + ulWrite = ptRingBuf->ulWriteIndex; + ulRead = ptRingBuf->ulReadIndex; + + // + // Return the full status of the buffer. + // + return((((ulWrite + 1) % ptRingBuf->ulSize) == ulRead) ? true : false); +} + +//***************************************************************************** +// +//! Determines whether the ring buffer whose pointers and size are provided +//! is empty or not. +//! +//! \param ptRingBuf is the ring buffer object to empty. +//! +//! This function is used to determine whether or not a given ring buffer is +//! empty. The structure is specifically to ensure that we do not see +//! warnings from the compiler related to the order of volatile accesses +//! being undefined. +//! +//! \return Returns \b true if the buffer is empty or \b false otherwise. +// +//***************************************************************************** +tBoolean +RingBufEmpty(tRingBufObject *ptRingBuf) +{ + unsigned long ulWrite; + unsigned long ulRead; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Copy the Read/Write indices for calculation. + // + ulWrite = ptRingBuf->ulWriteIndex; + ulRead = ptRingBuf->ulReadIndex; + + // + // Return the empty status of the buffer. + // + return((ulWrite == ulRead) ? true : false); +} + +//***************************************************************************** +// +//! Empties the ring buffer. +//! +//! \param ptRingBuf is the ring buffer object to empty. +//! +//! Discards all data from the ring buffer. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufFlush(tRingBufObject *ptRingBuf) +{ + tBoolean bIntsOff; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Set the Read/Write pointers to be the same. Do this with interrupts + // disabled to prevent the possibility of corruption of the read index. + // + bIntsOff = IntMasterDisable(); + ptRingBuf->ulReadIndex = ptRingBuf->ulWriteIndex; + if(!bIntsOff) + { + IntMasterEnable(); + } +} + +//***************************************************************************** +// +//! Returns number of bytes stored in ring buffer. +//! +//! \param ptRingBuf is the ring buffer object to check. +//! +//! This function returns the number of bytes stored in the ring buffer. +//! +//! \return Returns the number of bytes stored in the ring buffer. +// +//***************************************************************************** +unsigned long +RingBufUsed(tRingBufObject *ptRingBuf) +{ + unsigned long ulWrite; + unsigned long ulRead; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Copy the Read/Write indices for calculation. + // + ulWrite = ptRingBuf->ulWriteIndex; + ulRead = ptRingBuf->ulReadIndex; + + // + // Return the number of bytes contained in the ring buffer. + // + return((ulWrite >= ulRead) ? (ulWrite - ulRead) : + (ptRingBuf->ulSize - (ulRead - ulWrite))); +} + +//***************************************************************************** +// +//! Returns number of bytes available in a ring buffer. +//! +//! \param ptRingBuf is the ring buffer object to check. +//! +//! This function returns the number of bytes available in the ring buffer. +//! +//! \return Returns the number of bytes available in the ring buffer. +// +//***************************************************************************** +unsigned long +RingBufFree(tRingBufObject *ptRingBuf) +{ + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Return the number of bytes available in the ring buffer. + // + return((ptRingBuf->ulSize - 1) - RingBufUsed(ptRingBuf)); +} + +//***************************************************************************** +// +//! Returns number of contiguous bytes of data stored in ring buffer ahead of +//! the current read pointer. +//! +//! \param ptRingBuf is the ring buffer object to check. +//! +//! This function returns the number of contiguous bytes of data available in +//! the ring buffer ahead of the current read pointer. This represents the +//! largest block of data which does not straddle the buffer wrap. +//! +//! \return Returns the number of contiguous bytes available. +// +//***************************************************************************** +unsigned long +RingBufContigUsed(tRingBufObject *ptRingBuf) +{ + unsigned long ulWrite; + unsigned long ulRead; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Copy the Read/Write indices for calculation. + // + ulWrite = ptRingBuf->ulWriteIndex; + ulRead = ptRingBuf->ulReadIndex; + + // + // Return the number of contiguous bytes available. + // + return((ulWrite >= ulRead) ? (ulWrite - ulRead) : + (ptRingBuf->ulSize - ulRead)); +} + +//***************************************************************************** +// +//! Returns number of contiguous free bytes available in a ring buffer. +//! +//! \param ptRingBuf is the ring buffer object to check. +//! +//! This function returns the number of contiguous free bytes ahead of the +//! current write pointer in the ring buffer. +//! +//! \return Returns the number of contiguous bytes available in the ring +//! buffer. +// +//***************************************************************************** +unsigned long +RingBufContigFree(tRingBufObject *ptRingBuf) +{ + unsigned long ulWrite; + unsigned long ulRead; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Copy the Read/Write indices for calculation. + // + ulWrite = ptRingBuf->ulWriteIndex; + ulRead = ptRingBuf->ulReadIndex; + + // + // Return the number of contiguous bytes available. + // + if(ulRead > ulWrite) + { + // + // The read pointer is above the write pointer so the amount of free + // space is the difference between the two indices minus 1 to account + // for the buffer full condition (write index one behind read index). + // + return((ulRead - ulWrite) - 1); + } + else + { + // + // If the write pointer is above the read pointer, the amount of free + // space is the size of the buffer minus the write index. We need to + // add a special-case adjustment if the read index is 0 since we need + // to leave 1 byte empty to ensure we can tell the difference between + // the buffer being full and empty. + // + return(ptRingBuf->ulSize - ulWrite - ((ulRead == 0) ? 1 : 0)); + } +} + +//***************************************************************************** +// +//! Return size in bytes of a ring buffer. +//! +//! \param ptRingBuf is the ring buffer object to check. +//! +//! This function returns the size of the ring buffer. +//! +//! \return Returns the size in bytes of the ring buffer. +// +//***************************************************************************** +unsigned long +RingBufSize(tRingBufObject *ptRingBuf) +{ + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Return the number of bytes available in the ring buffer. + // + return(ptRingBuf->ulSize); +} + +//***************************************************************************** +// +//! Reads a single byte of data from a ring buffer. +//! +//! \param ptRingBuf points to the ring buffer to be written to. +//! +//! This function reads a single byte of data from a ring buffer. +//! +//! \return The byte read from the ring buffer. +// +//***************************************************************************** +unsigned char +RingBufReadOne(tRingBufObject *ptRingBuf) +{ + unsigned char ucTemp; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Verify that space is available in the buffer. + // + ASSERT(RingBufUsed(ptRingBuf) != 0); + + // + // Write the data byte. + // + ucTemp = ptRingBuf->pucBuf[ptRingBuf->ulReadIndex]; + + // + // Increment the read index. + // + UpdateIndexAtomic(&ptRingBuf->ulReadIndex, 1, ptRingBuf->ulSize); + + // + // Return the character read. + // + return(ucTemp); +} + +//***************************************************************************** +// +//! Reads data from a ring buffer. +//! +//! \param ptRingBuf points to the ring buffer to be read from. +//! \param pucData points to where the data should be stored. +//! \param ulLength is the number of bytes to be read. +//! +//! This function reads a sequence of bytes from a ring buffer. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufRead(tRingBufObject *ptRingBuf, unsigned char *pucData, + unsigned long ulLength) +{ + unsigned long ulTemp; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + ASSERT(pucData != NULL); + ASSERT(ulLength != 0); + + // + // Verify that data is available in the buffer. + // + ASSERT(ulLength <= RingBufUsed(ptRingBuf)); + + // + // Read the data from the ring buffer. + // + for(ulTemp = 0; ulTemp < ulLength; ulTemp++) + { + pucData[ulTemp] = RingBufReadOne(ptRingBuf); + } +} + +//***************************************************************************** +// +//! Remove bytes from the ring buffer by advancing the read index. +//! +//! \param ptRingBuf points to the ring buffer from which bytes are to be +//! removed. +//! \param ulNumBytes is the number of bytes to be removed from the buffer. +//! +//! This function advances the ring buffer read index by a given number of +//! bytes, removing that number of bytes of data from the buffer. If \e +//! ulNumBytes is larger than the number of bytes currently in the buffer, the +//! buffer is emptied. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufAdvanceRead(tRingBufObject *ptRingBuf, + unsigned long ulNumBytes) +{ + unsigned long ulCount; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Make sure that we are not being asked to remove more data than is + // there to be removed. + // + ulCount = RingBufUsed(ptRingBuf); + ulCount = (ulCount < ulNumBytes) ? ulCount : ulNumBytes; + + // + // Advance the buffer read index by the required number of bytes. + // + UpdateIndexAtomic(&ptRingBuf->ulReadIndex, ulCount, + ptRingBuf->ulSize); +} + +//***************************************************************************** +// +//! Add bytes to the ring buffer by advancing the write index. +//! +//! \param ptRingBuf points to the ring buffer to which bytes have been added. +//! \param ulNumBytes is the number of bytes added to the buffer. +//! +//! This function should be used by clients who wish to add data to the buffer +//! directly rather than via calls to RingBufWrite() or RingBufWriteOne(). It +//! advances the write index by a given number of bytes. If the \e ulNumBytes +//! parameter is larger than the amount of free space in the buffer, the +//! read pointer will be advanced to cater for the addition. Note that this +//! will result in some of the oldest data in the buffer being discarded. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufAdvanceWrite(tRingBufObject *ptRingBuf, + unsigned long ulNumBytes) +{ + unsigned long ulCount; + tBoolean bIntsOff; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Make sure we were not asked to add a silly number of bytes. + // + ASSERT(ulNumBytes <= ptRingBuf->ulSize); + + // + // Determine how much free space we currently think the buffer has. + // + ulCount = RingBufFree(ptRingBuf); + + // + // Advance the buffer write index by the required number of bytes and + // check that we have not run past the read index. Note that we must do + // this within a critical section (interrupts disabled) to prevent + // race conditions that could corrupt one or other of the indices. + // + bIntsOff = IntMasterDisable(); + + // + // Update the write pointer. + // + ptRingBuf->ulWriteIndex += ulNumBytes; + + // + // Check and correct for wrap. + // + if(ptRingBuf->ulWriteIndex >= ptRingBuf->ulSize) + { + ptRingBuf->ulWriteIndex -= ptRingBuf->ulSize; + } + + // + // Did the client add more bytes than the buffer had free space for? + // + if(ulCount < ulNumBytes) + { + // + // Yes - we need to advance the read pointer to ahead of the write + // pointer to discard some of the oldest data. + // + ptRingBuf->ulReadIndex = ptRingBuf->ulWriteIndex + 1; + + // + // Correct for buffer wrap if necessary. + // + if(ptRingBuf->ulReadIndex >= ptRingBuf->ulSize) + { + ptRingBuf->ulReadIndex -= ptRingBuf->ulSize; + } + } + + // + // Restore interrupts if we turned them off earlier. + // + if(!bIntsOff) + { + IntMasterEnable(); + } +} + +//***************************************************************************** +// +//! Writes a single byte of data to a ring buffer. +//! +//! \param ptRingBuf points to the ring buffer to be written to. +//! \param ucData is the byte to be written. +//! +//! This function writes a single byte of data into a ring buffer. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufWriteOne(tRingBufObject *ptRingBuf, unsigned char ucData) +{ + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + + // + // Verify that space is available in the buffer. + // + ASSERT(RingBufFree(ptRingBuf) != 0); + + // + // Write the data byte. + // + ptRingBuf->pucBuf[ptRingBuf->ulWriteIndex] = ucData; + + // + // Increment the write index. + // + UpdateIndexAtomic(&ptRingBuf->ulWriteIndex, 1, ptRingBuf->ulSize); +} + +//***************************************************************************** +// +//! Writes data to a ring buffer. +//! +//! \param ptRingBuf points to the ring buffer to be written to. +//! \param pucData points to the data to be written. +//! \param ulLength is the number of bytes to be written. +//! +//! This function write a sequence of bytes into a ring buffer. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufWrite(tRingBufObject *ptRingBuf, unsigned char *pucData, + unsigned long ulLength) +{ + unsigned long ulTemp; + + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + ASSERT(pucData != NULL); + ASSERT(ulLength != 0); + + // + // Verify that space is available in the buffer. + // + ASSERT(ulLength <= RingBufFree(ptRingBuf)); + + // + // Write the data into the ring buffer. + // + for(ulTemp = 0; ulTemp < ulLength; ulTemp++) + { + RingBufWriteOne(ptRingBuf, pucData[ulTemp]); + } +} + +//***************************************************************************** +// +//! Initialize a ring buffer object. +//! +//! \param ptRingBuf points to the ring buffer to be initialized. +//! \param pucBuf points to the data buffer to be used for the ring buffer. +//! \param ulSize is the size of the buffer in bytes. +//! +//! This function initializes a ring buffer object, preparing it to store data. +//! +//! \return None. +// +//***************************************************************************** +void +RingBufInit(tRingBufObject *ptRingBuf, unsigned char *pucBuf, + unsigned long ulSize) +{ + // + // Check the arguments. + // + ASSERT(ptRingBuf != NULL); + ASSERT(pucBuf != NULL); + ASSERT(ulSize != 0); + + // + // Initialize the ring buffer object. + // + ptRingBuf->ulSize = ulSize; + ptRingBuf->pucBuf = pucBuf; + ptRingBuf->ulWriteIndex = ptRingBuf->ulReadIndex = 0; +} + +//***************************************************************************** +// +// Close the Doxygen group. +//! @} +// +//***************************************************************************** -- cgit v1.3.1