4 files changed, 44 insertions, 65 deletions
diff --git a/prog/src/main.c b/prog/src/main.c
index 082172d..a31196f 100644
--- a/prog/src/main.c
+++ b/prog/src/main.c
@@ -1,13 +1,12 @@
 #include <stdint.h>
 
-//volatile uint32_t *io_in  = (volatile uint32_t *)0x00000000;
-//volatile uint32_t *io_out = (volatile uint32_t *)0x00000004; 
+volatile uint32_t *io_in  = (volatile uint32_t *)0x00000000;
+volatile uint32_t *io_out = (volatile uint32_t *)0x00000004;
+
 
 int main(void) {
   while (1) {
-    for (int i = 0; i < 32; ++i) {
-      *((volatile uint32_t *)0x00000004) = i;
-      for (int j = 0; j < 1024 * 128; ++j);
-    }
+    if (*io_in) *io_out = 0b00000;
+    else *io_out = 0b11111;
   }
 }
diff --git a/prog/src/prog.s b/prog/src/prog.s.tst
index ec227a9..ec227a9 100644
--- a/prog/src/prog.s
+++ b/prog/src/prog.s.tst
diff --git a/prog/src/startup.c b/prog/src/startup.c
new file mode 100644
index 0000000..32aa131
--- /dev/null
+++ b/prog/src/startup.c
@@ -0,0 +1,39 @@
+extern unsigned int _sidata; /* Start address for the .data section in ROM */
+extern unsigned int _sdata;  /* Start address for the .data section in RAM */
+extern unsigned int _edata;  /* End address for the .data section in RAM */
+extern unsigned int _sbss;   /* Start address for the .bss section */
+extern unsigned int _ebss;   /* End address for the .bss section */
+extern unsigned int _estack; /* End address for the stack section */
+
+void main(void);             /* The main function declaration */
+void _start(void) __attribute__((section(".text.startup"), naked)); /* The entry point */
+
+void _start(void)
+{
+    unsigned int *src, *dest;
+
+    /* Copy .data section from ROM to RAM */
+    src = &_sidata;  /* ROM address of the .data section */
+    for (dest = &_sdata; dest < &_edata;)
+    {
+        *dest++ = *src++;
+    }
+
+    //while(1);
+
+    /* Zero initialize .bss section */
+    for (dest = &_sbss; dest < &_ebss;)
+    {
+        *dest++ = 0;
+    }
+
+
+    /* Initialize stack pointer */
+    asm volatile ("la sp, _estack");
+
+    /* Call the main function */
+    main();
+
+    /* If main returns, loop forever */
+    while (1);
+}
diff --git a/prog/src/startup.s b/prog/src/startup.s
deleted file mode 100644
index 963c288..0000000
--- a/prog/src/startup.s
+++ /dev/null
@@ -1,59 +0,0 @@
-.section .init
-.globl _start
-_start:
-
-prog:
-/*
-    la t0, 4
-    la t1, 1
-
-    sw t1, 0(t0)
-
-    la t0, 0x00100000
-    li t1, 1
-    sw t1, 0(t0)
-    lw t2, 0(t0)
-
-    
-    j halt
-
-*/
-    /* Set up stack pointer */
-    la sp, _stack_end
-
-    /* Initialize .data section (copy from LMA to VMA) */
-    la t0, _sdata       /* VMA start of .data */
-    la t1, _edata       /* VMA end of .data */
-    la t2, _etext       /* LMA start of .data in flash */
-copy_data:
-    beq t0, t1, clear_bss
-    lw t3, 0(t2)
-    sw t3, 0(t0)
-    addi t0, t0, 4
-    addi t2, t2, 4
-    j copy_data
-
-clear_bss:
-    /* Clear .bss section */
-    la t0, _sbss        /* VMA start of .bss */
-    la t1, _ebss        /* VMA end of .bss */
-clear_loop:
-    beq t0, t1, init_libc
-    sw x0, 0(t0)
-    addi t0, t0, 4
-    j clear_loop
-
-init_libc:
-    /* Call libc initialization functions */
-    /* call _init */
-
-    /* Call main function */
-    call main
-
-finalize_libc:
-    /* Call libc finalization functions */
-    /* call _fini */
-
-halt:
-    /* Infinite loop after main returns */
-    j halt