Diff: main.cpp

Revision:

0:1f96d36a994f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jun 03 04:06:57 2012 +0000
@@ -0,0 +1,173 @@
+#include "mbed.h"
+
+#include <stdio.h>
+#include <string.h>
+
+// Found on the web @
+// http://simplestcodings.blogspot.com.au/2010/08/custom-malloc-function-implementation.html
+
+extern "C" void HardFault_Handler() {
+    printf("Hard Fault!\n");
+}
+
+Serial pc(USBTX, USBRX); // tx, rx
+
+char extmem[0x4000] __attribute__((section("AHBSRAM1")));
+
+typedef
+struct
+{
+    int is_available;
+    int size;
+} MCB, *MCB_P;
+
+
+char *mem_start_p;
+int max_mem;
+int allocated_mem; /* this is the memory in use. */
+int mcb_count;
+
+char *heap_end;
+
+MCB_P memallocate(MCB_P ,int );
+
+enum {NEW_MCB=0,NO_MCB,REUSE_MCB};
+enum {FREE,IN_USE};
+
+
+void * myalloc(int elem_size) {
+    /* check whether any chunk (allocated before) is free first */
+
+    MCB_P p_mcb;
+    int flag = NO_MCB;
+    int sz;
+
+    p_mcb = (MCB_P)mem_start_p;
+
+
+    sz = sizeof(MCB);
+
+    if ( (elem_size + sz) > (max_mem - (allocated_mem + mcb_count * sz ) ) ) {
+        return NULL;
+    }
+    while ( heap_end > ( (char *)p_mcb + elem_size + sz) ) { //<<-- problem here doesnt iterate the first block
+
+        if ( p_mcb->is_available == 0) {
+
+            if ( p_mcb->size == 0) {
+             //   printf("\NEW mem: %d ",p_mcb->size);  
+                flag = NEW_MCB;
+                break;
+            }
+            if ( p_mcb->size >= (elem_size + sz) ) {
+             //   printf("\REUSE mem: %d ",p_mcb->size); 
+                flag = REUSE_MCB;
+                break;
+            }
+        }
+        p_mcb = (MCB_P) ( (char *)p_mcb + p_mcb->size);
+
+
+    }
+
+    if ( flag != NO_MCB) {
+        p_mcb->is_available = 1;
+
+        if ( flag == NEW_MCB) {
+            p_mcb->size = elem_size + sizeof(MCB);
+        } else if ( flag == REUSE_MCB) {
+            elem_size = p_mcb->size - sizeof(MCB);
+        }
+        mcb_count++;
+        allocated_mem += elem_size;
+        return ( (char *) p_mcb + sz);
+    }
+
+    return NULL;
+
+
+    /* if size of the available chunk is equal to greater than required size, use that chunk */
+
+
+}
+
+void myfree(void *p) {
+    /* Mark in MCB that this chunk is free */
+   
+    MCB_P ptr = (MCB_P)p;
+    ptr--;
+
+    if (ptr->is_available != FREE) {
+        mcb_count--;
+        ptr->is_available = FREE;
+        allocated_mem -= (ptr->size - sizeof(MCB));
+    }
+    
+    /* Mark in MCB that this chunk is free */  
+    /*
+    MCB_P ptr = (MCB_P)p;   
+    ptr--;  
+ 
+    mcb_count--;  
+    ptr->is_available = FREE;  
+    printf("\nAllocated mem: %d ",ptr->size);  
+    allocated_mem -= (ptr->size - sizeof(MCB));  
+    printf("\nAllocated mem: %d ",allocated_mem);  
+    printf("\nMemory Freed...");  
+    */
+}
+
+void * myrealloc(void *p) {
+    //I would like to implement this
+    return NULL;
+}
+
+void InitMem(char *ptr, int size_in_bytes) {
+    /* store the ptr and size_in_bytes in global variable */
+
+    max_mem = size_in_bytes;
+    mem_start_p = ptr;
+    mcb_count = 0;
+    allocated_mem = 0;
+    heap_end = mem_start_p + size_in_bytes;
+    memset(mem_start_p,0x00,max_mem);
+    myalloc(2); //<<-- myalloc doesnt iterate the first block, added as temporary fix
+    /* This function is complete :-) */
+
+}
+
+
+int main() {
+
+    pc.baud(57600);
+    InitMem(extmem,sizeof(extmem));
+
+    int blockSize = 256;
+    int i = 1;
+
+    printf("Checking extmem memory with blocksize %d char ...\n", blockSize);
+    while (true) {
+        char *p = (char *) myalloc(i * blockSize);
+        printf("%d @ 0x%08X\n", i * blockSize, p);
+      //  printf("\nMCB count: %-3d \tAllocated Memory: %-10d",mcb_count,allocated_mem); 
+        if (p == NULL)
+            break;
+        myfree(p);
+        ++i;
+    }
+    printf("%d\n\r",(i - 1) * blockSize);
+
+/*
+   printf("Checking main memory with blocksize %d char ...\n", blockSize);
+    while (true) {
+        char *p = (char *) malloc(i * blockSize);
+        printf("%d @ 0x%08X\n", i * blockSize, p);
+        if (p == NULL)
+            break;
+        free(p);
+        ++i;
+    }
+    printf("%d\n\r",(i - 1) * blockSize);
+*/
+}
+