Diff: MemFileSystem.h

Revision:

11:2f7ad4af3ec1

Parent:

3:e960e2b81a3c

Child:

12:d816f503fc6f

--- a/MemFileSystem.h	Sun Mar 13 19:11:54 2016 +0000
+++ b/MemFileSystem.h	Thu Jul 20 10:58:56 2017 +0000
@@ -8,45 +8,52 @@
 
 #include "FATFileSystem.h"
 
+// 4 Bytes / Sector, each 512 Bytes - malloc'd as required
+// Value was 2000 (8K)
+#define NUM_SECTORS 500
+#define SECTOR_SIZE 512
+
+// moved the zeroed RAM buffer to flash, 
+// so it doesn't waste precious RAM
+static const char zero[SECTOR_SIZE] = {0};
+
 namespace mbed
 {
-
     class MemFileSystem : public FATFileSystem
     {
     public:
-    
-        // 2000 sectors, each 512 bytes (malloced as required)
-        char *sectors[2000];
+        // NUM_SECTORS sectors, each 512 bytes (malloced as required)
+        char *sectors[NUM_SECTORS];
     
         MemFileSystem(const char* name) : FATFileSystem(name) {
             memset(sectors, 0, sizeof(sectors));
         }
-    
+
         virtual ~MemFileSystem() {
-            for(int i = 0; i < 2000; i++) {
+            for(int i = 0; i < NUM_SECTORS; i++) {
                 if(sectors[i]) {
                     free(sectors[i]);
                 }
             }
         }
-    
+
         // read a sector in to the buffer, return 0 if ok
         virtual int disk_read(char *buffer, int sector) {
             if(sectors[sector] == 0) {
                 // nothing allocated means sector is empty
-                memset(buffer, 0, 512);
+                memset(buffer, 0, SECTOR_SIZE);
             } else {
-                memcpy(buffer, sectors[sector], 512);
+                memcpy(buffer, sectors[sector], SECTOR_SIZE);
             }
             return 0;
         }
-    
+
         // write a sector from the buffer, return 0 if ok
         virtual int disk_write(const char *buffer, int sector) {
             // if buffer is zero deallocate sector
-            char zero[512];
-            memset(zero, 0, 512);
-            if(memcmp(zero, buffer, 512)==0) {
+            //char zero[SECTOR_SIZE] = {0};     // DS this used to be a ram buffer
+            //memset(zero, 0, SECTOR_SIZE);
+            if(memcmp(zero, buffer, SECTOR_SIZE)==0) {
                 if(sectors[sector] != 0) {
                     free(sectors[sector]);
                     sectors[sector] = 0;
@@ -55,23 +62,21 @@
             }
             // else allocate a sector if needed, and write
             if(sectors[sector] == 0) {
-                char *sec = (char*)malloc(512);
+                char *sec = (char*)malloc(SECTOR_SIZE);
                 if(sec==0) {
                     return 1; // out of memory
                 }
                 sectors[sector] = sec;
             }
-            memcpy(sectors[sector], buffer, 512);
+            memcpy(sectors[sector], buffer, SECTOR_SIZE);
             return 0;
         }
-    
+
         // return the number of sectors
         virtual int disk_sectors() {
             return sizeof(sectors)/sizeof(sectors[0]);
         }
-    
     };
-
 }
 
 #endif
\ No newline at end of file