Espresso 0.0.2a

drivers/fs/ssfs.c

@@ -0,0 +1,117 @@
+#include <types.h>
+#include <string.h>
+#include <stdlib.h>
+#include <math.h>
+#include <drivers/ide.h>
+
+#include <fs/ssfs.h>
+
+
+
+#define SSFS_START_LBA 16
+#define SSFS_FILE_HEADER_SIZE_BYTES 32
+
+
+int ssfs_read_file(const char* name, void* buffer, int size)
+{
+  if (strlen(name) > 15)
+  {
+    return -1;
+  }
+  
+  uint8_t header_buf[512];
+  int r = read_sector(16, header_buf);
+  
+  if (r != 0)
+  {
+    return -2;
+  }
+
+  ssfs_file_header_t f;
+  memcpy(&f, header_buf, sizeof(f));
+
+  if (strncmp(f.filename, name, 15) != 0)
+  {
+    return -3;
+  }
+
+  /* Clamp read size to actual file size */
+  if (size > (int)f.num_bytes)
+      size = (int)f.num_bytes;
+
+  int total_read = 0;
+  int sector_count = div_round_up(size, 512);
+  uint8_t sector_data[512];
+
+  for (int k = 0; k < sector_count; k++)
+  {
+    r = read_sector(f.start_sector + k, sector_data);
+    
+    if (r != 0)
+    {
+      return -4; /* I/O error */
+    }
+
+    int to_copy = size - total_read;
+    
+    if (to_copy > 512)
+    {
+      to_copy = 512;
+    }
+
+    memcpy((uint8_t*)buffer + total_read, sector_data, to_copy);
+    total_read += to_copy;
+  }
+
+  return 0;
+}
+
+
+/* size is number of bytes */
+int ssfs_write_file(const char* name, void* data, int size)
+{
+  ssfs_file_header_t* f = (ssfs_file_header_t*) malloc(sizeof(ssfs_file_header_t));
+  memset(f, 0, sizeof(ssfs_file_header_t));
+  
+  if (strlen(name) > 15)
+  {
+    return -1;
+  }
+  
+  strcpy(f->filename, name);
+  f->num_sectors = 0;
+  
+  int sector_count = div_round_up(size, 512);
+  
+  uint8_t* buffer = (uint8_t*) malloc(sector_count * 512);
+  
+  memset(buffer, 0, sector_count * 512);
+  memcpy(buffer, data, (size_t) size);
+  
+  int r = 0;
+  
+  f->start_sector = 32;
+  
+  for (int k = 0; k < sector_count; k++)
+  {
+    r = write_sector(f->start_sector + k, buffer + (k * 512));
+    
+    if (r != 0)
+    {
+      break;
+    }
+  }
+  
+  f->num_sectors = sector_count;
+  f->num_bytes = (uint32_t) size;
+  
+  uint8_t header_buf[512];
+  memset(header_buf, 0, 512);
+  memcpy(header_buf, f, sizeof(*f));
+  write_sector(16, header_buf);
+  
+  free(buffer);
+  free(f);
+  
+  return 0;
+}