355 lines
16 KiB
C
355 lines
16 KiB
C
/**************************************************************************/
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/* */
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/* Copyright (c) Microsoft Corporation. All rights reserved. */
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/* */
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/* This software is licensed under the Microsoft Software License */
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/* Terms for Microsoft Azure RTOS. Full text of the license can be */
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/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
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/* and in the root directory of this software. */
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/* */
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/**************************************************************************/
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/**************************************************************************/
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/**************************************************************************/
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/** */
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/** ThreadX Component */
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/** */
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/** Byte Pool */
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/** */
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/**************************************************************************/
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/**************************************************************************/
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#define TX_SOURCE_CODE
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/* Include necessary system files. */
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#include "tx_api.h"
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#include "tx_thread.h"
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#include "tx_byte_pool.h"
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/**************************************************************************/
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/* */
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/* FUNCTION RELEASE */
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/* */
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/* _tx_byte_pool_search PORTABLE C */
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/* 6.1.7 */
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/* AUTHOR */
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/* */
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/* William E. Lamie, Microsoft Corporation */
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/* */
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/* DESCRIPTION */
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/* */
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/* This function searches a byte pool for a memory block to satisfy */
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/* the requested number of bytes. Merging of adjacent free blocks */
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/* takes place during the search and a split of the block that */
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/* satisfies the request may occur before this function returns. */
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/* */
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/* It is assumed that this function is called with interrupts enabled */
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/* and with the tx_pool_owner field set to the thread performing the */
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/* search. Also note that the search can occur during allocation and */
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/* release of a memory block. */
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/* */
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/* INPUT */
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/* */
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/* pool_ptr Pointer to pool control block */
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/* memory_size Number of bytes required */
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/* */
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/* OUTPUT */
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/* */
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/* UCHAR * Pointer to the allocated memory, */
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/* if successful. Otherwise, a */
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/* NULL is returned */
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/* */
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/* CALLS */
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/* */
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/* None */
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/* */
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/* CALLED BY */
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/* */
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/* _tx_byte_allocate Allocate bytes of memory */
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/* _tx_byte_release Release bytes of memory */
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/* */
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/* RELEASE HISTORY */
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/* */
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/* DATE NAME DESCRIPTION */
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/* */
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/* 05-19-2020 William E. Lamie Initial Version 6.0 */
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/* 09-30-2020 Yuxin Zhou Modified comment(s), */
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/* resulting in version 6.1 */
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/* 06-02-2021 Scott Larson Improve possible free bytes */
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/* calculation, */
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/* resulting in version 6.1.7 */
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/* */
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/**************************************************************************/
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UCHAR *_tx_byte_pool_search(TX_BYTE_POOL *pool_ptr, ULONG memory_size)
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{
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TX_INTERRUPT_SAVE_AREA
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UCHAR *current_ptr;
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UCHAR *next_ptr;
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UCHAR **this_block_link_ptr;
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UCHAR **next_block_link_ptr;
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ULONG available_bytes;
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UINT examine_blocks;
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UINT first_free_block_found = TX_FALSE;
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TX_THREAD *thread_ptr;
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ALIGN_TYPE *free_ptr;
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UCHAR *work_ptr;
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ULONG total_theoretical_available;
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/* Disable interrupts. */
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TX_DISABLE
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/* First, determine if there are enough bytes in the pool. */
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/* Theoretical bytes available = free bytes + ((fragments-2) * overhead of each block) */
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total_theoretical_available = pool_ptr -> tx_byte_pool_available + ((pool_ptr -> tx_byte_pool_fragments - 2) * ((sizeof(UCHAR *)) + (sizeof(ALIGN_TYPE))));
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if (memory_size >= total_theoretical_available)
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{
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/* Restore interrupts. */
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TX_RESTORE
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/* Not enough memory, return a NULL pointer. */
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current_ptr = TX_NULL;
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}
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else
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{
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/* Pickup thread pointer. */
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TX_THREAD_GET_CURRENT(thread_ptr)
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/* Setup ownership of the byte pool. */
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pool_ptr -> tx_byte_pool_owner = thread_ptr;
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/* Walk through the memory pool in search for a large enough block. */
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current_ptr = pool_ptr -> tx_byte_pool_search;
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examine_blocks = pool_ptr -> tx_byte_pool_fragments + ((UINT) 1);
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available_bytes = ((ULONG) 0);
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do
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{
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#ifdef TX_BYTE_POOL_ENABLE_PERFORMANCE_INFO
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/* Increment the total fragment search counter. */
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_tx_byte_pool_performance_search_count++;
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/* Increment the number of fragments searched on this pool. */
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pool_ptr -> tx_byte_pool_performance_search_count++;
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#endif
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/* Check to see if this block is free. */
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work_ptr = TX_UCHAR_POINTER_ADD(current_ptr, (sizeof(UCHAR *)));
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free_ptr = TX_UCHAR_TO_ALIGN_TYPE_POINTER_CONVERT(work_ptr);
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if ((*free_ptr) == TX_BYTE_BLOCK_FREE)
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{
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/* Determine if this is the first free block. */
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if (first_free_block_found == TX_FALSE)
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{
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/* This is the first free block. */
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pool_ptr->tx_byte_pool_search = current_ptr;
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/* Set the flag to indicate we have found the first free
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block. */
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first_free_block_found = TX_TRUE;
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}
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/* Block is free, see if it is large enough. */
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/* Pickup the next block's pointer. */
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this_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(current_ptr);
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next_ptr = *this_block_link_ptr;
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/* Calculate the number of bytes available in this block. */
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available_bytes = TX_UCHAR_POINTER_DIF(next_ptr, current_ptr);
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available_bytes = available_bytes - ((sizeof(UCHAR *)) + (sizeof(ALIGN_TYPE)));
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/* If this is large enough, we are done because our first-fit algorithm
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has been satisfied! */
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if (available_bytes >= memory_size)
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{
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/* Get out of the search loop! */
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break;
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}
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else
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{
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/* Clear the available bytes variable. */
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available_bytes = ((ULONG) 0);
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/* Not enough memory, check to see if the neighbor is
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free and can be merged. */
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work_ptr = TX_UCHAR_POINTER_ADD(next_ptr, (sizeof(UCHAR *)));
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free_ptr = TX_UCHAR_TO_ALIGN_TYPE_POINTER_CONVERT(work_ptr);
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if ((*free_ptr) == TX_BYTE_BLOCK_FREE)
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{
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/* Yes, neighbor block can be merged! This is quickly accomplished
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by updating the current block with the next blocks pointer. */
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next_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(next_ptr);
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*this_block_link_ptr = *next_block_link_ptr;
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/* Reduce the fragment total. We don't need to increase the bytes
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available because all free headers are also included in the available
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count. */
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pool_ptr -> tx_byte_pool_fragments--;
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#ifdef TX_BYTE_POOL_ENABLE_PERFORMANCE_INFO
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/* Increment the total merge counter. */
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_tx_byte_pool_performance_merge_count++;
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/* Increment the number of blocks merged on this pool. */
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pool_ptr -> tx_byte_pool_performance_merge_count++;
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#endif
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/* See if the search pointer is affected. */
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if (pool_ptr -> tx_byte_pool_search == next_ptr)
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{
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/* Yes, update the search pointer. */
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pool_ptr -> tx_byte_pool_search = current_ptr;
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}
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}
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else
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{
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/* Neighbor is not free so we can skip over it! */
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next_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(next_ptr);
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current_ptr = *next_block_link_ptr;
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/* Decrement the examined block count to account for this one. */
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if (examine_blocks != ((UINT) 0))
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{
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examine_blocks--;
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#ifdef TX_BYTE_POOL_ENABLE_PERFORMANCE_INFO
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/* Increment the total fragment search counter. */
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_tx_byte_pool_performance_search_count++;
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/* Increment the number of fragments searched on this pool. */
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pool_ptr -> tx_byte_pool_performance_search_count++;
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#endif
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}
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}
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}
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}
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else
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{
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/* Block is not free, move to next block. */
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this_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(current_ptr);
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current_ptr = *this_block_link_ptr;
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}
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/* Another block has been searched... decrement counter. */
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if (examine_blocks != ((UINT) 0))
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{
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examine_blocks--;
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}
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/* Restore interrupts temporarily. */
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TX_RESTORE
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/* Disable interrupts. */
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TX_DISABLE
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/* Determine if anything has changed in terms of pool ownership. */
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if (pool_ptr -> tx_byte_pool_owner != thread_ptr)
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{
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/* Pool changed ownership in the brief period interrupts were
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enabled. Reset the search. */
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current_ptr = pool_ptr -> tx_byte_pool_search;
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examine_blocks = pool_ptr -> tx_byte_pool_fragments + ((UINT) 1);
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/* Setup our ownership again. */
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pool_ptr -> tx_byte_pool_owner = thread_ptr;
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}
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} while(examine_blocks != ((UINT) 0));
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/* Determine if a block was found. If so, determine if it needs to be
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split. */
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if (available_bytes != ((ULONG) 0))
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{
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/* Determine if we need to split this block. */
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if ((available_bytes - memory_size) >= ((ULONG) TX_BYTE_BLOCK_MIN))
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{
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/* Split the block. */
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next_ptr = TX_UCHAR_POINTER_ADD(current_ptr, (memory_size + ((sizeof(UCHAR *)) + (sizeof(ALIGN_TYPE)))));
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/* Setup the new free block. */
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next_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(next_ptr);
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this_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(current_ptr);
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*next_block_link_ptr = *this_block_link_ptr;
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work_ptr = TX_UCHAR_POINTER_ADD(next_ptr, (sizeof(UCHAR *)));
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free_ptr = TX_UCHAR_TO_ALIGN_TYPE_POINTER_CONVERT(work_ptr);
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*free_ptr = TX_BYTE_BLOCK_FREE;
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/* Increase the total fragment counter. */
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pool_ptr -> tx_byte_pool_fragments++;
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/* Update the current pointer to point at the newly created block. */
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*this_block_link_ptr = next_ptr;
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/* Set available equal to memory size for subsequent calculation. */
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available_bytes = memory_size;
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#ifdef TX_BYTE_POOL_ENABLE_PERFORMANCE_INFO
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/* Increment the total split counter. */
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_tx_byte_pool_performance_split_count++;
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/* Increment the number of blocks split on this pool. */
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pool_ptr -> tx_byte_pool_performance_split_count++;
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#endif
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}
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/* In any case, mark the current block as allocated. */
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work_ptr = TX_UCHAR_POINTER_ADD(current_ptr, (sizeof(UCHAR *)));
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this_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(work_ptr);
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*this_block_link_ptr = TX_BYTE_POOL_TO_UCHAR_POINTER_CONVERT(pool_ptr);
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/* Reduce the number of available bytes in the pool. */
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pool_ptr -> tx_byte_pool_available = (pool_ptr -> tx_byte_pool_available - available_bytes) - ((sizeof(UCHAR *)) + (sizeof(ALIGN_TYPE)));
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/* Determine if the search pointer needs to be updated. This is only done
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if the search pointer matches the block to be returned. */
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if (current_ptr == pool_ptr -> tx_byte_pool_search)
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{
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/* Yes, update the search pointer to the next block. */
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this_block_link_ptr = TX_UCHAR_TO_INDIRECT_UCHAR_POINTER_CONVERT(current_ptr);
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pool_ptr -> tx_byte_pool_search = *this_block_link_ptr;
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}
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/* Restore interrupts. */
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TX_RESTORE
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/* Adjust the pointer for the application. */
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current_ptr = TX_UCHAR_POINTER_ADD(current_ptr, (((sizeof(UCHAR *)) + (sizeof(ALIGN_TYPE)))));
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}
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else
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{
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/* Restore interrupts. */
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TX_RESTORE
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/* Set current pointer to NULL to indicate nothing was found. */
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current_ptr = TX_NULL;
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}
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}
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/* Return the search pointer. */
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return(current_ptr);
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}
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