revised block device structure

Author: totalspectrum

Changelog.txt

@@ -8,6 +8,7 @@ Version 7.0.0
 - Fixed incorrect handling of simple for loops with unsigned variables
 - Improved some debug error messages
 - Only use the stack for variables whose address is actually taken (thanks to Ada for this!)
+- Modified _BlockDevice data structure (used for littlefs, but someday may be used for fatfs too)
 
 Version 6.9.10
 - Fix compilation error when GETWORD is replaced by MOV or MUL

include/filesys/littlefs/lfswrapper.cc

@@ -20,20 +20,13 @@ static _BlockDevice *Default_SPI_Init(unsigned offset, unsigned used_size, unsig
 {
     static _SpiFlash spi;
     static _BlockDevice blk;
-    static char read_cache[SPI_PROG_SIZE];
-    static char prog_cache[SPI_PROG_SIZE];
-    static char lookahead_cache[SPI_PROG_SIZE];
 
     spi.Init(offset, used_size, erase_size);
     blk.blk_read = &spi.Read;
     blk.blk_write = &spi.WritePage;
     blk.blk_erase = &spi.Erase;
     blk.blk_sync = &spi.Sync;
 
-    blk.read_cache = read_cache;
-    blk.write_cache = prog_cache;
-    blk.lookahead_cache = lookahead_cache;
-    
     return &blk;
 }
 
@@ -97,6 +90,10 @@ static int _flash_sync(const struct lfs_config *cfg) {
 static int _flash_create(struct lfs_config *cfg, struct littlefs_flash_config *flashcfg)
 {
     _BlockDevice *blk = flashcfg->dev;
+    static bool default_cache_used = false;
+    static char read_cache[SPI_PROG_SIZE];
+    static char prog_cache[SPI_PROG_SIZE];
+    static char lookahead_cache[SPI_PROG_SIZE];
 
     if (!blk) {
         blk = Default_SPI_Init(flashcfg->offset, flashcfg->used_size, flashcfg->erase_size);
@@ -123,10 +120,18 @@ static int _flash_create(struct lfs_config *cfg, struct littlefs_flash_config *f
     cfg->block_cycles = 400;
 
     // buffers
-    cfg->read_buffer = blk->read_cache;
-    cfg->prog_buffer = blk->write_cache;
-    cfg->lookahead_buffer = blk->lookahead_cache;
-    
+    if (default_cache_used) {
+        // dynamically allocate more memory
+        int blksize = SPI_PROG_SIZE;
+        cfg->read_buffer = malloc(blksize);
+        cfg->prog_buffer = malloc(blksize);
+        cfg->lookahead_buffer = malloc(blksize);
+    } else {
+        cfg->read_buffer = read_cache;
+        cfg->prog_buffer = prog_cache;
+        cfg->lookahead_buffer = lookahead_cache;
+        default_cache_used = true;
+    }
     // set up block device operations
     cfg->read = _flash_read;
     cfg->prog = _flash_prog;

include/sys/vfs.h

@@ -57,15 +57,23 @@ int _mkfs_parallaxfs(void) _IMPL("filesys/parallax/parallaxfs_vfs.c");
 /* block read/write device */
 typedef struct block_device {
     /* functions for doing I/O */
+
+    /* read an arbitrary number of bytes (need not be block aligned */
     int (*blk_read)(void *dst, unsigned long flashAdr, unsigned long size);
+
+    /* write & erase blocks (erase may be a no-op if not required) */
     int (*blk_write)(void *src, unsigned long flashAdr);  // write one block
     int (*blk_erase)(unsigned long flashAdr);             // erase one block
+
+    /* sync to device */
     int (*blk_sync)(void);
 
-    /* buffers for the I/O */
-    char *read_cache;
-    char *write_cache;
-    char *lookahead_cache;
+    /* general ioctl */
+    int (*blk_ioctl)(int request, void *arg);
+
+    /* block size */
+    int blksize;
+    
 } _BlockDevice;
 
 /* structure for configuring a littlefs flash file system */