Initial Commit

1 files changed, 64 insertions, 0 deletions

diff --git a/VexRiscvSocSoftware/projects/murax/wip/src/crt.c b/VexRiscvSocSoftware/projects/murax/wip/src/crt.c
new file mode 100644
index 0000000..70e6c06
--- /dev/null
+++ b/VexRiscvSocSoftware/projects/murax/wip/src/crt.c
@@ -0,0 +1,64 @@
+/*
+Created by: roman3017
+Inspired by: https://jacobmossberg.se/posts/2018/08/11/run-c-program-bare-metal-on-arm-cortex-m3.html
+*/
+
+extern unsigned int __global_pointer$;
+extern unsigned int _stack_start;
+extern unsigned int _bss_start;
+extern unsigned int _bss_end;
+extern unsigned int _ctors_start;
+extern unsigned int _ctors_end;
+
+void crtStart();
+void irqCallback();
+void main();
+
+static void trapEntry();
+static void bssInit();
+static void ctorsInit();
+
+unsigned int * initVectors[2] __attribute__ ((section("vectors"))) = {
+  (unsigned int *) crtStart,    // code entry
+  (unsigned int *) trapEntry,   // trap entry
+};
+
+void crtStart()
+{
+  /* Initialize sp and gp registers */
+  asm volatile (
+    "la gp, %0\n\t"
+    "la sp, %1\n\t"
+    :: "i"(&__global_pointer$), "i"(&_stack_start)
+  );
+
+  bssInit();
+  ctorsInit();
+  main();
+  asm volatile("j .");
+}
+
+static void trapEntry()
+{
+  irqCallback();
+}
+
+static void bssInit()
+{
+  unsigned int * bss_start_p = &_bss_start; 
+  unsigned int * bss_end_p = &_bss_end;
+  while(bss_start_p != bss_end_p) {
+    *bss_start_p++ = 0;
+  }
+}
+
+static void ctorsInit()
+{
+  unsigned int * ctors_start_p = &_ctors_start;
+  unsigned int * ctors_end_p = &_ctors_end;
+  void(*ctor)(); 
+  while(ctors_start_p != ctors_end_p) {
+    ctor = (void *)*ctors_start_p++;
+    ctor();
+  }
+}