Merge branch 'bob' of https://repo.or.cz/RPi-MMU-example into alice

# Conflicts:
#	.gitignore
#	PL0_test.ld
#	demo_functionality.c
#	interrupt_vector.S
#	interrupts.c
#	kernel.c
#	memory.h

1 files changed, 65 insertions, 0 deletions

diff --git a/ramfs.c b/ramfs.c
new file mode 100644
index 0000000..cc66b4c
--- /dev/null
+++ b/ramfs.c
@@ -0,0 +1,65 @@
+// driver for the read-only ramfs
+// see makefs.c for details
+
+#include <stdint.h>
+#include "ramfs.h"
+
+static int strcmp(char const *str1, char const *str2)
+{
+  while (1)
+    {
+      int c1 = (unsigned char) *str1, c2 = (unsigned char) *str2;
+      
+      if (!c1 && !c2)
+	return 0;
+
+      if (c1 != c2)
+	return c1 - c2;
+
+      str1++; str2++;
+    }
+}
+
+static uint32_t strlen(char const *str1)
+{
+  uint32_t len = 0;
+
+  while (str1[len])
+    len++;
+
+  return len;
+}
+
+static inline char *align4(char *addr)
+{
+  return (char*) (((uint32_t) addr - 1) & ~0b11) + 4;
+}
+
+int find_file(void *ramfs, char *filename, struct ramfile *buf)
+{
+  char *fs_file = ramfs;
+
+  while (*fs_file)
+    {
+      uint32_t *fs_file_size = (uint32_t*)
+	align4(fs_file + strlen(fs_file) + 1);
+      
+      char *fs_file_contents = (char*) (fs_file_size + 1);
+
+      if (!strcmp(fs_file, filename))
+	{
+	  buf->file_size = *fs_file_size;
+
+	  buf->file_name = fs_file;
+
+	  buf->file_contents = fs_file_contents;
+	  
+	  return 0;
+	}
+
+      // move to the next file in ramfs
+      fs_file = align4(fs_file_contents + *fs_file_size);
+    }
+
+  return -1; // reached end of ramfs; file not found
+}