add initial bootloader work

1 files changed, 30 insertions, 0 deletions

diff --git a/loader_stage1.c b/loader_stage1.c
new file mode 100644
index 0000000..9492747
--- /dev/null
+++ b/loader_stage1.c
@@ -0,0 +1,30 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <uart.h>
+#include <global.h>
+
+char *const stage2_addr = ((void*) 0x4000);
+
+// there's one tricky thing about embedding file in executable;
+// mainly, symbols are visible to c code as extern chars, but the actual
+// values are their adresses... see the code below
+extern char
+  _binary_loader_stage2_img_start,
+  _binary_loader_stage2_img_end,
+  _binary_loader_stage2_img_size;
+
+void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags)
+{
+  // uart_init() call to be moved to stage2...
+  uart_init();
+  uart_puts("Hello, bootloader World!\r\n");
+
+  // stage2 of the bootloader is a blob embedded in executable;
+  // copy it over to it's destination place
+  // TODO implement a memcpy() somewhere and use it instead of loops
+  for (size_t i = 0; i < (size_t) &_binary_loader_stage2_img_size; i++)
+    stage2_addr[i] = (&_binary_loader_stage2_img_start)[i];
+
+  // jump to stage2
+  ((void(*)(uint32_t, uint32_t, uint32_t))stage2_addr)(r0, r1, atags);
+}