mymalloc - malloc for reserved memory banks

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Jason Engelman / Mbed 2 deprecated mymalloc

malloc for reserved memory banks

main.cpp@0:1f96d36a994f, 2012-06-03 (annotated)

Committer:: tecnosys
Date:: Sun Jun 03 04:06:57 2012 +0000
Revision:: 0:1f96d36a994f

Who changed what in which revision?

User	Revision	Line number	New contents of line
tecnosys	0:1f96d36a994f	1	#include "mbed.h"
tecnosys	0:1f96d36a994f	2
tecnosys	0:1f96d36a994f	3	#include <stdio.h>
tecnosys	0:1f96d36a994f	4	#include <string.h>
tecnosys	0:1f96d36a994f	5
tecnosys	0:1f96d36a994f	6	// Found on the web @
tecnosys	0:1f96d36a994f	7	// http://simplestcodings.blogspot.com.au/2010/08/custom-malloc-function-implementation.html
tecnosys	0:1f96d36a994f	8
tecnosys	0:1f96d36a994f	9	extern "C" void HardFault_Handler() {
tecnosys	0:1f96d36a994f	10	printf("Hard Fault!\n");
tecnosys	0:1f96d36a994f	11	}
tecnosys	0:1f96d36a994f	12
tecnosys	0:1f96d36a994f	13	Serial pc(USBTX, USBRX); // tx, rx
tecnosys	0:1f96d36a994f	14
tecnosys	0:1f96d36a994f	15	char extmem[0x4000] __attribute__((section("AHBSRAM1")));
tecnosys	0:1f96d36a994f	16
tecnosys	0:1f96d36a994f	17	typedef
tecnosys	0:1f96d36a994f	18	struct
tecnosys	0:1f96d36a994f	19	{
tecnosys	0:1f96d36a994f	20	int is_available;
tecnosys	0:1f96d36a994f	21	int size;
tecnosys	0:1f96d36a994f	22	} MCB, *MCB_P;
tecnosys	0:1f96d36a994f	23
tecnosys	0:1f96d36a994f	24
tecnosys	0:1f96d36a994f	25	char *mem_start_p;
tecnosys	0:1f96d36a994f	26	int max_mem;
tecnosys	0:1f96d36a994f	27	int allocated_mem; /* this is the memory in use. */
tecnosys	0:1f96d36a994f	28	int mcb_count;
tecnosys	0:1f96d36a994f	29
tecnosys	0:1f96d36a994f	30	char *heap_end;
tecnosys	0:1f96d36a994f	31
tecnosys	0:1f96d36a994f	32	MCB_P memallocate(MCB_P ,int );
tecnosys	0:1f96d36a994f	33
tecnosys	0:1f96d36a994f	34	enum {NEW_MCB=0,NO_MCB,REUSE_MCB};
tecnosys	0:1f96d36a994f	35	enum {FREE,IN_USE};
tecnosys	0:1f96d36a994f	36
tecnosys	0:1f96d36a994f	37
tecnosys	0:1f96d36a994f	38	void * myalloc(int elem_size) {
tecnosys	0:1f96d36a994f	39	/* check whether any chunk (allocated before) is free first */
tecnosys	0:1f96d36a994f	40
tecnosys	0:1f96d36a994f	41	MCB_P p_mcb;
tecnosys	0:1f96d36a994f	42	int flag = NO_MCB;
tecnosys	0:1f96d36a994f	43	int sz;
tecnosys	0:1f96d36a994f	44
tecnosys	0:1f96d36a994f	45	p_mcb = (MCB_P)mem_start_p;
tecnosys	0:1f96d36a994f	46
tecnosys	0:1f96d36a994f	47
tecnosys	0:1f96d36a994f	48	sz = sizeof(MCB);
tecnosys	0:1f96d36a994f	49
tecnosys	0:1f96d36a994f	50	if ( (elem_size + sz) > (max_mem - (allocated_mem + mcb_count * sz ) ) ) {
tecnosys	0:1f96d36a994f	51	return NULL;
tecnosys	0:1f96d36a994f	52	}
tecnosys	0:1f96d36a994f	53	while ( heap_end > ( (char *)p_mcb + elem_size + sz) ) { //<<-- problem here doesnt iterate the first block
tecnosys	0:1f96d36a994f	54
tecnosys	0:1f96d36a994f	55	if ( p_mcb->is_available == 0) {
tecnosys	0:1f96d36a994f	56
tecnosys	0:1f96d36a994f	57	if ( p_mcb->size == 0) {
tecnosys	0:1f96d36a994f	58	// printf("\NEW mem: %d ",p_mcb->size);
tecnosys	0:1f96d36a994f	59	flag = NEW_MCB;
tecnosys	0:1f96d36a994f	60	break;
tecnosys	0:1f96d36a994f	61	}
tecnosys	0:1f96d36a994f	62	if ( p_mcb->size >= (elem_size + sz) ) {
tecnosys	0:1f96d36a994f	63	// printf("\REUSE mem: %d ",p_mcb->size);
tecnosys	0:1f96d36a994f	64	flag = REUSE_MCB;
tecnosys	0:1f96d36a994f	65	break;
tecnosys	0:1f96d36a994f	66	}
tecnosys	0:1f96d36a994f	67	}
tecnosys	0:1f96d36a994f	68	p_mcb = (MCB_P) ( (char *)p_mcb + p_mcb->size);
tecnosys	0:1f96d36a994f	69
tecnosys	0:1f96d36a994f	70
tecnosys	0:1f96d36a994f	71	}
tecnosys	0:1f96d36a994f	72
tecnosys	0:1f96d36a994f	73	if ( flag != NO_MCB) {
tecnosys	0:1f96d36a994f	74	p_mcb->is_available = 1;
tecnosys	0:1f96d36a994f	75
tecnosys	0:1f96d36a994f	76	if ( flag == NEW_MCB) {
tecnosys	0:1f96d36a994f	77	p_mcb->size = elem_size + sizeof(MCB);
tecnosys	0:1f96d36a994f	78	} else if ( flag == REUSE_MCB) {
tecnosys	0:1f96d36a994f	79	elem_size = p_mcb->size - sizeof(MCB);
tecnosys	0:1f96d36a994f	80	}
tecnosys	0:1f96d36a994f	81	mcb_count++;
tecnosys	0:1f96d36a994f	82	allocated_mem += elem_size;
tecnosys	0:1f96d36a994f	83	return ( (char *) p_mcb + sz);
tecnosys	0:1f96d36a994f	84	}
tecnosys	0:1f96d36a994f	85
tecnosys	0:1f96d36a994f	86	return NULL;
tecnosys	0:1f96d36a994f	87
tecnosys	0:1f96d36a994f	88
tecnosys	0:1f96d36a994f	89	/* if size of the available chunk is equal to greater than required size, use that chunk */
tecnosys	0:1f96d36a994f	90
tecnosys	0:1f96d36a994f	91
tecnosys	0:1f96d36a994f	92	}
tecnosys	0:1f96d36a994f	93
tecnosys	0:1f96d36a994f	94	void myfree(void *p) {
tecnosys	0:1f96d36a994f	95	/* Mark in MCB that this chunk is free */
tecnosys	0:1f96d36a994f	96
tecnosys	0:1f96d36a994f	97	MCB_P ptr = (MCB_P)p;
tecnosys	0:1f96d36a994f	98	ptr--;
tecnosys	0:1f96d36a994f	99
tecnosys	0:1f96d36a994f	100	if (ptr->is_available != FREE) {
tecnosys	0:1f96d36a994f	101	mcb_count--;
tecnosys	0:1f96d36a994f	102	ptr->is_available = FREE;
tecnosys	0:1f96d36a994f	103	allocated_mem -= (ptr->size - sizeof(MCB));
tecnosys	0:1f96d36a994f	104	}
tecnosys	0:1f96d36a994f	105
tecnosys	0:1f96d36a994f	106	/* Mark in MCB that this chunk is free */
tecnosys	0:1f96d36a994f	107	/*
tecnosys	0:1f96d36a994f	108	MCB_P ptr = (MCB_P)p;
tecnosys	0:1f96d36a994f	109	ptr--;
tecnosys	0:1f96d36a994f	110
tecnosys	0:1f96d36a994f	111	mcb_count--;
tecnosys	0:1f96d36a994f	112	ptr->is_available = FREE;
tecnosys	0:1f96d36a994f	113	printf("\nAllocated mem: %d ",ptr->size);
tecnosys	0:1f96d36a994f	114	allocated_mem -= (ptr->size - sizeof(MCB));
tecnosys	0:1f96d36a994f	115	printf("\nAllocated mem: %d ",allocated_mem);
tecnosys	0:1f96d36a994f	116	printf("\nMemory Freed...");
tecnosys	0:1f96d36a994f	117	*/
tecnosys	0:1f96d36a994f	118	}
tecnosys	0:1f96d36a994f	119
tecnosys	0:1f96d36a994f	120	void * myrealloc(void *p) {
tecnosys	0:1f96d36a994f	121	//I would like to implement this
tecnosys	0:1f96d36a994f	122	return NULL;
tecnosys	0:1f96d36a994f	123	}
tecnosys	0:1f96d36a994f	124
tecnosys	0:1f96d36a994f	125	void InitMem(char *ptr, int size_in_bytes) {
tecnosys	0:1f96d36a994f	126	/* store the ptr and size_in_bytes in global variable */
tecnosys	0:1f96d36a994f	127
tecnosys	0:1f96d36a994f	128	max_mem = size_in_bytes;
tecnosys	0:1f96d36a994f	129	mem_start_p = ptr;
tecnosys	0:1f96d36a994f	130	mcb_count = 0;
tecnosys	0:1f96d36a994f	131	allocated_mem = 0;
tecnosys	0:1f96d36a994f	132	heap_end = mem_start_p + size_in_bytes;
tecnosys	0:1f96d36a994f	133	memset(mem_start_p,0x00,max_mem);
tecnosys	0:1f96d36a994f	134	myalloc(2); //<<-- myalloc doesnt iterate the first block, added as temporary fix
tecnosys	0:1f96d36a994f	135	/* This function is complete :-) */
tecnosys	0:1f96d36a994f	136
tecnosys	0:1f96d36a994f	137	}
tecnosys	0:1f96d36a994f	138
tecnosys	0:1f96d36a994f	139
tecnosys	0:1f96d36a994f	140	int main() {
tecnosys	0:1f96d36a994f	141
tecnosys	0:1f96d36a994f	142	pc.baud(57600);
tecnosys	0:1f96d36a994f	143	InitMem(extmem,sizeof(extmem));
tecnosys	0:1f96d36a994f	144
tecnosys	0:1f96d36a994f	145	int blockSize = 256;
tecnosys	0:1f96d36a994f	146	int i = 1;
tecnosys	0:1f96d36a994f	147
tecnosys	0:1f96d36a994f	148	printf("Checking extmem memory with blocksize %d char ...\n", blockSize);
tecnosys	0:1f96d36a994f	149	while (true) {
tecnosys	0:1f96d36a994f	150	char p = (char ) myalloc(i * blockSize);
tecnosys	0:1f96d36a994f	151	printf("%d @ 0x%08X\n", i * blockSize, p);
tecnosys	0:1f96d36a994f	152	// printf("\nMCB count: %-3d \tAllocated Memory: %-10d",mcb_count,allocated_mem);
tecnosys	0:1f96d36a994f	153	if (p == NULL)
tecnosys	0:1f96d36a994f	154	break;
tecnosys	0:1f96d36a994f	155	myfree(p);
tecnosys	0:1f96d36a994f	156	++i;
tecnosys	0:1f96d36a994f	157	}
tecnosys	0:1f96d36a994f	158	printf("%d\n\r",(i - 1) * blockSize);
tecnosys	0:1f96d36a994f	159
tecnosys	0:1f96d36a994f	160	/*
tecnosys	0:1f96d36a994f	161	printf("Checking main memory with blocksize %d char ...\n", blockSize);
tecnosys	0:1f96d36a994f	162	while (true) {
tecnosys	0:1f96d36a994f	163	char p = (char ) malloc(i * blockSize);
tecnosys	0:1f96d36a994f	164	printf("%d @ 0x%08X\n", i * blockSize, p);
tecnosys	0:1f96d36a994f	165	if (p == NULL)
tecnosys	0:1f96d36a994f	166	break;
tecnosys	0:1f96d36a994f	167	free(p);
tecnosys	0:1f96d36a994f	168	++i;
tecnosys	0:1f96d36a994f	169	}
tecnosys	0:1f96d36a994f	170	printf("%d\n\r",(i - 1) * blockSize);
tecnosys	0:1f96d36a994f	171	*/
tecnosys	0:1f96d36a994f	172	}
tecnosys	0:1f96d36a994f	173

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	03 Jun 2012
Imports:	2
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	1

main.cpp@0:1f96d36a994f, 2012-06-03 (annotated)

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