236 lines
9 KiB
C
236 lines
9 KiB
C
//***************************************************************************************
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// MPB memory allocation routines.
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//***************************************************************************************
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//
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// Author: Rob F. Van der Wijngaart
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// Intel Corporation
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// Date: 12/22/2010
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//
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//***************************************************************************************
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//
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// Copyright 2010 Intel Corporation
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#include <asm/RCCE_lib.h>
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#ifdef CONFIG_ROCKCREEK
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//......................................................................................
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// GLOBAL VARIABLES USED BY THE LIBRARY
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//......................................................................................
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static RCCE_BLOCK_S RCCE_space; // data structure used for trscking MPB memory blocks
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static RCCE_BLOCK_S *RCCE_spacep; // pointer to RCCE_space
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#ifdef _OPENMP
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#pragma omp threadprivate (RCCE_space, RCCE_spacep)
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#endif
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// END GLOBAL VARIABLES USED BY THE LIBRARY
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//......................................................................................
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//--------------------------------------------------------------------------------------
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// FUNCTION: RCCE_malloc_init
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//--------------------------------------------------------------------------------------
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// initialize memory allocator
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//--------------------------------------------------------------------------------------
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void RCCE_malloc_init(
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t_vcharp mem, // pointer to MPB space that is to be managed by allocator
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size_t size // size (bytes) of managed space
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) {
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#ifndef GORY
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// in the simplified API MPB memory allocation merely uses running pointers
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RCCE_flags_start = mem;
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RCCE_chunk = size;
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RCCE_buff_ptr = mem;
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#else
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// create one block containing all memory for truly dynamic memory allocator
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RCCE_spacep = &RCCE_space;
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RCCE_spacep->tail = (RCCE_BLOCK *) kmalloc(sizeof(RCCE_BLOCK));
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RCCE_spacep->tail->free_size = size;
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RCCE_spacep->tail->space = mem;
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/* make a circular list by connecting tail to itself */
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RCCE_spacep->tail->next = RCCE_spacep->tail;
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#endif
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}
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//--------------------------------------------------------------------------------------
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// FUNCTION: RCCE_malloc
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//--------------------------------------------------------------------------------------
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// Allocate memory inside MPB. In restricted mode we only use it to allocate new
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// flags prompted by the creation of new communicators. Since communicators are never
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// deleted, we do not need to deallocate MPB memory, so we can simply keep running
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// pointers of where the next flag will be stored, and where payload data can go. In
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// GORY mode we need to support fully dynamic memory allocation and deallocation.
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//--------------------------------------------------------------------------------------
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t_vcharp RCCE_malloc(
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size_t size // requested space
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) {
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t_vcharp result;
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#ifndef GORY
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// new flag takes exactly one cache line, whether using single bit flags or not
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if (size != RCCE_LINE_SIZE) return(0);
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// if chunk size becomes zero, we have allocated too many flags
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if (!(RCCE_chunk-RCCE_LINE_SIZE)) return(0);
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result = RCCE_flags_start;
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// reduce maximum size of message payload chunk
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RCCE_chunk -= RCCE_LINE_SIZE;
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// move running pointer to next available flags line
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RCCE_flags_start +=RCCE_LINE_SIZE;
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// move running pointer to new start of payload data area
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RCCE_buff_ptr +=RCCE_LINE_SIZE;
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return(result);
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#else
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// simple memory allocator, loosely based on public domain code developed by
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// Michael B. Allen and published on "The Scripts--IT /Developers Network".
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// Approach:
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// - maintain linked list of pointers to memory. A block is either completely
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// malloced (free_size = 0), or completely free (free_size > 0).
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// The space field always points to the beginning of the block
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// - malloc: traverse linked list for first block that has enough space
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// - free: Check if pointer exists. If yes, check if the new block should be
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// merged with neighbors. Could be one or two neighbors.
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RCCE_BLOCK *b1, *b2, *b3; // running pointers for blocks
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if (size==0 || size%RCCE_LINE_SIZE!=0) return 0;
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// always first check if the tail block has enough space, because that
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// is the most likely. If it does and it is exactly enough, we still
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// create a new block that will be the new tail, whose free space is
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// zero. This acts as a marker of where free space of predecessor ends
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b1 = RCCE_spacep->tail;
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if (b1->free_size >= size) {
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// need to insert new block; new order is: b1->b2 (= new tail)
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b2 = (RCCE_BLOCK *) kmalloc(sizeof(RCCE_BLOCK));
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b2->next = b1->next;
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b1->next = b2;
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b2->free_size = b1->free_size-size;
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b2->space = b1->space + size;
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b1->free_size = 0;
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// need to update the tail
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RCCE_spacep->tail = b2;
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return(b1->space);
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}
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// tail didn't have enough space; loop over whole list from beginning
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while (b1->next->free_size < size) {
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if (b1->next == RCCE_spacep->tail) {
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return NULL; // we came full circle
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}
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b1 = b1->next;
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}
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b2 = b1->next;
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if (b2->free_size > size) { // split block; new block order: b1->b2->b3
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b3 = (RCCE_BLOCK *) kmalloc(sizeof(RCCE_BLOCK));
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b3->next = b2->next; // reconnect pointers to add block b3
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b2->next = b3; // " " " " " "
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b3->free_size = b2->free_size - size; // b3 gets remainder free space
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b3->space = b2->space + size; // need to shift space pointer
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}
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b2->free_size = 0; // block b2 is completely used
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return (b2->space);
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#endif
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}
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//--------------------------------------------------------------------------------------
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// FUNCTION: RCCE_free
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//--------------------------------------------------------------------------------------
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// Deallocate memory in MPB; only used in GORY mode
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//--------------------------------------------------------------------------------------
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void RCCE_free(
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t_vcharp ptr // pointer to data to be freed
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) {
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RCCE_BLOCK *b1, *b2, *b3; // running block pointers
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int j1, j2; // booleans determining merging of blocks
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// loop over whole list from the beginning until we locate space ptr
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b1 = RCCE_spacep->tail;
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while (b1->next->space != ptr && b1->next != RCCE_spacep->tail) {
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b1 = b1->next;
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}
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// b2 is target block whose space must be freed
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b2 = b1->next;
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// tail either has zero free space, or hasn't been malloc'ed
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if (b2 == RCCE_spacep->tail) return;
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// reset free space for target block (entire block)
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b3 = b2->next;
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b2->free_size = b3->space - b2->space;
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// determine with what non-empty blocks the target block can be merged
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j1 = (b1->free_size>0 && b1!=RCCE_spacep->tail); // predecessor block
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j2 = (b3->free_size>0 || b3==RCCE_spacep->tail); // successor block
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if (j1) {
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if (j2) { // splice all three blocks together: (b1,b2,b3) into b1
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b1->next = b3->next;
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b1->free_size += b3->free_size + b2->free_size;
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if (b3==RCCE_spacep->tail) RCCE_spacep->tail = b1;
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kfree(b3, sizeof(RCCE_BLOCK));
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}
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else { // only merge (b1,b2) into b1
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b1->free_size += b2->free_size;
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b1->next = b3;
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}
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kfree(b2, sizeof(RCCE_BLOCK));
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}
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else {
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if (j2) { // only merge (b2,b3) into b2
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b2->next = b3->next;
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b2->free_size += b3->free_size;
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if (b3==RCCE_spacep->tail) RCCE_spacep->tail = b2;
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kfree(b3, sizeof(RCCE_BLOCK));
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}
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}
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}
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//--------------------------------------------------------------------------------------
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// FUNCTION: RCCE_malloc_request
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//--------------------------------------------------------------------------------------
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// this function tries to return a (padded) amount of space in the MPB of size
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// "size" bytes. If not available, the function keeps halving space until it fits
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//--------------------------------------------------------------------------------------
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t_vcharp RCCE_malloc_request(
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size_t size, // requested number of bytes
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size_t *chunk // number of bytes of space returned
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) {
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t_vcharp combuf;
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combuf = 0;
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*chunk = PAD32byte(size);
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while (!combuf && *chunk >= RCCE_LINE_SIZE) {
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combuf = RCCE_malloc(*chunk);
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if (!combuf) *chunk = PAD32byte(*chunk/2);
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}
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return (combuf);
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}
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#endif
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