| //***************************************************************************** |
| // |
| //! @file am_util_ring_buffer.c |
| //! |
| //! @brief Some helper functions for implementing and managing a ring buffer. |
| // |
| //***************************************************************************** |
| |
| //***************************************************************************** |
| // |
| // Copyright (c) 2017, Ambiq Micro |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are met: |
| // |
| // 1. Redistributions of source code must retain the above copyright notice, |
| // this list of conditions and the following disclaimer. |
| // |
| // 2. Redistributions in binary form must reproduce the above copyright |
| // notice, this list of conditions and the following disclaimer in the |
| // documentation and/or other materials provided with the distribution. |
| // |
| // 3. Neither the name of the copyright holder nor the names of its |
| // contributors may be used to endorse or promote products derived from this |
| // software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| // POSSIBILITY OF SUCH DAMAGE. |
| // |
| // This is part of revision v1.2.10-2-gea660ad-hotfix2 of the AmbiqSuite Development Package. |
| // |
| //***************************************************************************** |
| |
| #include <stdint.h> |
| #include <stdbool.h> |
| #include "am_util_ring_buffer.h" |
| |
| //***************************************************************************** |
| // |
| //! @brief Initializes a ring buffer structure. |
| //! |
| //! @param psBuffer is a pointer to the buffer structure to be initialized. |
| //! |
| //! @param pvArray is a pointer to the array that the new ringbuffer will use |
| //! for storage space |
| //! |
| //! @param ui32Bytes is the total number of bytes that the ringbuffer will be |
| //! allowed to use. |
| //! |
| //! This function should be called on a ring buffer structure before it is |
| //! used. If this function is called on a ring buffer that is already being |
| //! used, it will "erase" the buffer, effectively removing all of the buffer |
| //! contents from the perspective of the other ring buffer access functions. |
| //! The data will remain in memory, but it will be overwritten as the buffer is |
| //! used. |
| //! |
| //! @note This operation is not inherently thread-safe, so the caller must make |
| //! sure that it is appropriately guarded from interrupts and context switches. |
| //! |
| //! @return |
| // |
| //***************************************************************************** |
| void |
| am_util_ring_buffer_init(am_util_ring_buffer_t *psBuffer, void *pvArray, |
| uint32_t ui32Bytes) |
| { |
| psBuffer->ui32WriteIndex = 0; |
| psBuffer->ui32ReadIndex = 0; |
| psBuffer->ui32Length = 0; |
| psBuffer->ui32Capacity = ui32Bytes; |
| psBuffer->pui8Data = (uint8_t *)pvArray; |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Write a single byte to the ring buffer. |
| //! |
| //! @param psBuffer is the address of the ring buffer structure to be written. |
| //! @param ui8Value is the byte to be added to the ring buffer. |
| //! |
| //! This function will write a single byte to the given ring buffer. Make sure |
| //! that the ring buffer is not already full when calling this function. If the |
| //! ring buffer is already full, this function will fail silently. |
| //! |
| //! @note This operation is not inherently thread-safe, so the caller must make |
| //! sure that it is appropriately guarded from interrupts and context switches. |
| //! |
| //! @return True if the data was written to the buffer. False for insufficient |
| //! space. |
| // |
| //***************************************************************************** |
| bool |
| am_util_ring_buffer_write(am_util_ring_buffer_t *psBuffer, void *pvSource, |
| uint32_t ui32Bytes) |
| { |
| uint32_t i; |
| uint8_t *pui8Source; |
| |
| pui8Source = (uint8_t *) pvSource; |
| |
| // |
| // Check to make sure that the buffer isn't already full |
| // |
| if ( am_util_ring_buffer_space_left(psBuffer) >= ui32Bytes ) |
| { |
| // |
| // Loop over the bytes in the source array. |
| // |
| for ( i = 0; i < ui32Bytes; i++ ) |
| { |
| // |
| // Write the value to the buffer. |
| // |
| psBuffer->pui8Data[psBuffer->ui32WriteIndex] = pui8Source[i]; |
| |
| // |
| // Advance the write index, making sure to wrap if necessary. |
| // |
| psBuffer->ui32WriteIndex = ((psBuffer->ui32WriteIndex + 1) % |
| psBuffer->ui32Capacity); |
| } |
| |
| // |
| // Update the length value appropriately. |
| // |
| psBuffer->ui32Length += ui32Bytes; |
| |
| // |
| // Report a success. |
| // |
| return true; |
| } |
| else |
| { |
| // |
| // The ring buffer can't fit the amount of data requested. Return a |
| // failure. |
| // |
| return false; |
| } |
| } |
| |
| //***************************************************************************** |
| // |
| //! @brief Read a single byte from the ring buffer. |
| //! |
| //! @param psBuffer is the address of the ring buffer structure to be read. |
| //! |
| //! This function will write a single byte to the given ring buffer. Make sure |
| //! that the ring buffer is not already empty. If the ring buffer is empty, |
| //! this function will just return a NULL character. |
| //! |
| //! @note This operation is not inherently thread-safe, so the caller must make |
| //! sure that it is appropriately guarded from interrupts and context switches. |
| //! |
| //! @return The byte read from the buffer, or a NULL if the buffer was empty. |
| // |
| //***************************************************************************** |
| bool |
| am_util_ring_buffer_read(am_util_ring_buffer_t *psBuffer, void *pvDest, |
| uint32_t ui32Bytes) |
| { |
| uint32_t i; |
| uint8_t *pui8Dest; |
| |
| pui8Dest = (uint8_t *) pvDest; |
| |
| // |
| // Check to make sure that the buffer isn't empty |
| // |
| if ( am_util_ring_buffer_data_left(psBuffer) >= ui32Bytes ) |
| { |
| // |
| // Loop over the bytes in the destination array. |
| // |
| for ( i = 0; i < ui32Bytes; i++ ) |
| { |
| // |
| // Grab the next value from the buffer. |
| // |
| pui8Dest[i] = psBuffer->pui8Data[psBuffer->ui32ReadIndex]; |
| |
| // |
| // Advance the read index, wrapping if needed. |
| // |
| psBuffer->ui32ReadIndex = ((psBuffer->ui32ReadIndex + 1) % |
| psBuffer->ui32Capacity); |
| } |
| |
| // |
| // Adjust the length value to reflect the change. |
| // |
| psBuffer->ui32Length -= ui32Bytes; |
| |
| // |
| // Report a success. |
| // |
| return true; |
| } |
| else |
| { |
| // |
| // If the buffer didn't have enough data, just return a zero. |
| // |
| return false; |
| } |
| } |