Implement file device

There is still a small amount of work to be done on the file device:
- Read file size only when requested
- Hide '.' and '..' directories
- Resize files

2 files changed, 70 insertions, 0 deletions

diff --git a/arm9/source/types/pathbuf.c b/arm9/source/types/pathbuf.c
new file mode 100644
index 0000000..1a610c8
--- /dev/null
+++ b/arm9/source/types/pathbuf.c
@@ -0,0 +1,52 @@
+#include <nds.h>
+#include "pathbuf.h"
+
+u8 pb_read(PathBuf *buf) {
+    u8 output = buf->mem[buf->p];
+    if (output) buf->p++;
+    return output;
+}
+
+void pb_clear(PathBuf *buf) {
+    memset(&buf->mem, 0, 256);
+}
+
+void pb_reset(PathBuf *buf, bool to_name) {
+    buf->p = 0;
+    if (to_name) for (int i=0; i<255; i++) {
+        if (buf->mem[i] == '/') {
+            buf->p = i+1;
+        } else if (buf->mem[i] == 0) {
+            break;
+        }
+    }
+}
+
+// Push a byte to a PathBuf, return true and reset the pointer if byte is null.
+bool pb_push_byte(PathBuf *buf, u8 byte) {
+    // Stop before overwriting the pointer.
+    if (buf->p != 0xff) {
+        buf->mem[buf->p++] = byte;
+    }
+    if (byte == 0) {
+        buf->p = 0;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool pb_is_terminated(PathBuf *buf) {
+    for (int i=0; i<255; i++) {
+        if (buf->mem[i] == 0) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void pb_populate(PathBuf *buf, u8 *path) {
+    strncpy((char*) &buf->mem[0], (char*) path, 254);
+    buf->p = 0;
+}
+
diff --git a/arm9/source/types/pathbuf.h b/arm9/source/types/pathbuf.h
new file mode 100644
index 0000000..7fd7251
--- /dev/null
+++ b/arm9/source/types/pathbuf.h
@@ -0,0 +1,18 @@
+#include <nds.h>
+
+#ifndef PATHBUF_H_
+    #define PATHBUF_H_
+
+    typedef struct {
+        u8 mem[255];
+        u8 p;
+    } PathBuf;
+
+    u8 pb_read(PathBuf *buf);
+    void pb_clear(PathBuf *buf);
+    void pb_reset(PathBuf *buf, bool to_name);
+    bool pb_push_byte(PathBuf *buf, u8 byte);
+    bool pb_is_terminated(PathBuf *buf);
+    void pb_populate(PathBuf *buf, u8 *path);
+
+#endif