/*------------------------------------------------------------------------- malloc.c - allocate memory. Copyright (C) 2004, Maarten Brock, sourceforge.brock@dse.nl This library is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this library; see the file COPYING. If not, write to the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. As a special exception, if you link this library with other files, some of which are compiled with SDCC, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. -------------------------------------------------------------------------*/ #include #include #if defined(__SDCC_STACK_AUTO) || defined(__SDCC_z80) || defined(__SDCC_z180) || defined(__SDCC_gbz80) #define CRITICAL __critical #else #define CRITICAL #endif #if _SDCC_MALLOC_TYPE_MLH typedef struct _MEMHEADER MEMHEADER; struct _MEMHEADER { MEMHEADER * next; MEMHEADER * prev; unsigned int len; unsigned char mem; }; #define HEADER_SIZE (sizeof(MEMHEADER)-sizeof(char)) /* These variables are defined through the crt0 functions. */ /* Base of this variable is the first byte of the heap. */ extern MEMHEADER _sdcc_heap_start; /* Address of this variable is the last byte of the heap. */ extern char _sdcc_heap_end; void _sdcc_heap_init(void) { MEMHEADER *pbase = &_sdcc_heap_start; unsigned int size = &_sdcc_heap_end - (char *)pbase; pbase->next = (MEMHEADER *)((char *)pbase + size - HEADER_SIZE); pbase->next->next = NULL; //And mark it as last pbase->prev = NULL; //and mark first as first pbase->len = 0; //Empty and ready. } void * malloc (unsigned int size) { register MEMHEADER * current_header; register MEMHEADER * new_header; register void * ret; if (size>(0xFFFF-HEADER_SIZE)) { return NULL; //To prevent overflow in next line } size += HEADER_SIZE; //We need a memory for header too current_header = &_sdcc_heap_start; CRITICAL { while (1) { // current // | len next // v v v //....*****.........******.... // ^^^^^^^^^ // spare if ((((unsigned int)current_header->next) - ((unsigned int)current_header) - current_header->len) >= size) { //if spare is more than needed ret = ¤t_header->mem; break; } current_header = current_header->next; //else try next if (!current_header->next) { //if end_of_list reached ret = NULL; break; } } if (ret) { if (!current_header->len) { //This code works only for first_header in the list and only current_header->len = size; //for first allocation } else { //else create new header at the begin of spare new_header = (MEMHEADER * )((char *)current_header + current_header->len); new_header->next = current_header->next; //and plug it into the chain new_header->prev = current_header; current_header->next = new_header; if (new_header->next) { new_header->next->prev = new_header; } new_header->len = size; //mark as used ret = &new_header->mem; } } } return ret; } #else //-------------------------------------------------------------------- //Written by Dmitry S. Obukhov, 1997 //dso@usa.net //-------------------------------------------------------------------- //Modified for SDCC by Sandeep Dutta, 1999 //sandeep.dutta@usa.net //-------------------------------------------------------------------- //malloc and free functions implementation for embedded system //Non-ANSI keywords are C51 specific. // __xdata - variable in external memory (just RAM) //-------------------------------------------------------------------- #define MEMHEADER struct MAH// Memory Allocation Header MEMHEADER { MEMHEADER __xdata * next; unsigned int len; unsigned char mem[]; }; #define HEADER_SIZE sizeof(MEMHEADER) MEMHEADER __xdata * _sdcc_first_memheader = NULL; extern __xdata char _sdcc_heap[]; extern const unsigned int _sdcc_heap_size; static void init_dynamic_memory(void) { char __xdata * heap = (char __xdata *)_sdcc_heap; unsigned int size = _sdcc_heap_size; if ( !heap ) //Reserved memory starts at 0x0000 but that's NULL... { //So, we lost one byte! heap++; size--; } _sdcc_first_memheader = (MEMHEADER __xdata * ) heap; //Reserve a mem for last header _sdcc_first_memheader->next = (MEMHEADER __xdata * )(heap + size - sizeof(MEMHEADER __xdata *)); _sdcc_first_memheader->next->next = (MEMHEADER __xdata * ) NULL; //And mark it as last _sdcc_first_memheader->len = 0; //Empty and ready. } void __xdata * malloc (unsigned int size) { register MEMHEADER __xdata * current_header; register MEMHEADER __xdata * new_header; register void __xdata * ret; if (size>(0xFFFF-HEADER_SIZE)) return (void __xdata *) NULL; //To prevent overflow in next line size += HEADER_SIZE; //We need a memory for header too if (!_sdcc_first_memheader) init_dynamic_memory(); current_header = _sdcc_first_memheader; CRITICAL { while (1) { // current // | len next // v v v //....*****.........******.... // ^^^^^^^^^ // spare if ((((unsigned int)current_header->next) - ((unsigned int)current_header) - current_header->len) >= size) { //if spare is more than needed ret = current_header->mem; break; } current_header = current_header->next; //else try next if (!current_header->next) { //if end_of_list reached ret = (void __xdata *) NULL; break; } } if (ret) { if (!current_header->len) { //This code works only for first_header in the list and only current_header->len = size; //for first allocation } else { //else create new header at the begin of spare new_header = (MEMHEADER __xdata * )((char __xdata *)current_header + current_header->len); new_header->next = current_header->next; //and plug it into the chain current_header->next = new_header; new_header->len = size; //mark as used ret = new_header->mem; } } } return ret; } //END OF MODULE #endif