Adding some romfs support.

1 files changed, 94 insertions, 0 deletions

diff --git a/os/src/romfs.c b/os/src/romfs.c
new file mode 100644
index 0000000..403bef9
--- /dev/null
+++ b/os/src/romfs.c
@@ -0,0 +1,94 @@
+#include <string.h>
+#include <FreeRTOS.h>
+#include <semphr.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "fio.h"
+#include "filesystem.h"
+#include "romfs.h"
+#include "osdebug.h"
+#include "hash-djb2.h"
+
+struct romfs_fds_t {
+    const uint8_t * file;
+    uint32_t cursor;
+};
+
+static struct romfs_fds_t romfs_fds[MAX_FDS];
+
+static uint32_t get_unaligned(const uint32_t * _d) {
+    const uint8_t * d = (const uint8_t *) _d;
+    return ((uint32_t) d[0]) | ((uint32_t) (d[1] << 8)) | ((uint32_t) (d[2] << 16)) | ((uint32_t) (d[3] << 24));
+}
+
+static ssize_t romfs_read(void * opaque, void * buf, size_t count) {
+    struct romfs_fds_t * f = (struct romfs_fds_t *) opaque;
+    const uint8_t * size_p = f->file - 4;
+    uint32_t size = get_unaligned((uint32_t *) size_p);
+    
+    if ((f->cursor + count) > size)
+        count = size - f->cursor;
+
+    memcpy(buf, f->file + f->cursor, count);
+    f->cursor += count;
+
+    return count;
+}
+
+static off_t romfs_seek(void * opaque, off_t offset, int whence) {
+    struct romfs_fds_t * f = (struct romfs_fds_t *) opaque;
+    const uint8_t * size_p = f->file - 4;
+    uint32_t size = get_unaligned((uint32_t *) size_p);
+    uint32_t origin;
+    
+    switch (whence) {
+    case SEEK_SET:
+        origin = 0;
+        break;
+    case SEEK_CUR:
+        origin = f->cursor;
+        break;
+    case SEEK_END:
+        origin = size;
+        break;
+    default:
+        return -1;
+    }
+
+    offset = origin + offset;
+
+    if (offset < 0)
+        return -1;
+    if (offset > size)
+        offset = size;
+
+    f->cursor = offset;
+
+    return offset;
+}
+
+static int romfs_open(void * opaque, const char * path, int flags, int mode) {
+    uint32_t h = hash_djb2((const uint8_t *) path, -1);
+    const uint8_t * romfs = (const uint8_t *) opaque;
+    const uint32_t * meta;
+    int r = -1;
+
+    for (meta = (uint32_t *) romfs; get_unaligned(meta) && get_unaligned(meta + 1); romfs = romfs + meta[1], meta = (uint32_t *) romfs) {
+        if (meta[0] == h) {
+            r = fio_open(romfs_read, NULL, romfs_seek, NULL, NULL);
+            if (r > 0) {
+                romfs_fds[r].file = romfs + 8;
+                romfs_fds[r].cursor = 0;
+                fio_set_opaque(r, romfs_fds + r);
+            }
+            break;
+        }
+    }
+    return r;
+}
+
+void register_romfs(const char * mountpoint, const uint8_t * romfs) {
+    register_fs(mountpoint, romfs_open, (void *) romfs);
+}