Expose raw reads/writes to store devs via dev interface

share/sysdefs/dev.h

@@ -1,6 +1,9 @@
 #ifndef SHARE_SYSDEFS_DEV_H_
 #define SHARE_SYSDEFS_DEV_H_
 
+#include <stdint.h>
+#include <stddef.h>
+
 #define DEV_TERMDEV_PUTCH 0
 
 #define DEV_PS2KBDEV_READCH     0
@@ -13,6 +16,25 @@
 
 #define DEV_FBDEV_GETINFO 0
 
+#define DEV_STOREDEV_READ       0
+#define DEV_STOREDEV_WRITE      1
+#define DEV_STOREDEV_SECCOUNT   2
+#define DEV_STOREDEV_SECTSIZE   3
+
+typedef struct {
+  uint8_t *const buffer;
+  ptrdiff_t sector;
+  ptrdiff_t off;
+  size_t size;
+} StoreDevRead;
+
+typedef struct {
+  const uint8_t *const buffer;
+  ptrdiff_t sector;
+  ptrdiff_t off;
+  size_t size;
+} StoreDevWrite;
+
 typedef uint64_t Dev_t;
 
 typedef struct {