From def3f62f7f8d6b5bd4b15500c7d11935540e81da Mon Sep 17 00:00:00 2001
From: Flavian Kaufmann <flavian@flaviankaufmann.ch>
Date: Wed, 15 May 2024 09:27:51 +0200
Subject: fixed relative memory addressing bug

---
 prog/link.ld        |  4 +--
 prog/src/main.c     |  2 ++
 prog/src/prog.s     | 78 +++++++++++++++++++++++++++++++++++++++++
 prog/src/prog.s.bak | 99 -----------------------------------------------------
 4 files changed, 82 insertions(+), 101 deletions(-)
 create mode 100644 prog/src/prog.s
 delete mode 100644 prog/src/prog.s.bak

(limited to 'prog')

diff --git a/prog/link.ld b/prog/link.ld
index 4cc02ec..7bd11eb 100644
--- a/prog/link.ld
+++ b/prog/link.ld
@@ -43,7 +43,7 @@ SECTIONS
     .stack (NOLOAD) :
     {
         _stack_start = .;
-        . += 0x10; /* Adjust the size as needed */
+        . += 0x80; /* Adjust the size as needed */
         _stack_end = .;
     } > RAM
 
@@ -51,7 +51,7 @@ SECTIONS
     .heap (NOLOAD) :
     {
         _heap_start = .;
-        . += 0x10; /* Adjust the size as needed */
+        . += 0x80; /* Adjust the size as needed */
         _heap_end = .;
     } > RAM
 }
diff --git a/prog/src/main.c b/prog/src/main.c
index 1ce067c..8bcdfe2 100644
--- a/prog/src/main.c
+++ b/prog/src/main.c
@@ -1,6 +1,8 @@
 
+extern void test_prog(void);
 
 int main(void) {
+  test_prog();
   while (1) {
   }
 }
diff --git a/prog/src/prog.s b/prog/src/prog.s
new file mode 100644
index 0000000..ec227a9
--- /dev/null
+++ b/prog/src/prog.s
@@ -0,0 +1,78 @@
+.section .text
+.globl test_prog
+
+
+/*
+  addi t0, zero, 31
+reset_loop:
+  addi t6, zero, 0
+loop:
+  addi t6, t6, 1
+  beq t6, t0, reset_loop
+  j loop
+*/
+
+test_prog:
+  li t0, 0xFFFFFFFF
+  li t1, 0x33333333
+  li t2, 0x88888888
+  li t3, 0x11111111
+
+  add   t4, t1,   t2
+  sub   t4, t1,   t2
+  slt   t4, t3,   t0
+  slt   t4, t0,   t3
+  sltu  t4, t3,   t0
+  sltu  t4, t0,   t3
+  and   t4, zero, zero
+  and   t4, zero, t0
+  and   t4, t0,   t0
+  or    t4, zero, zero
+  or    t4, zero, t0
+  or    t4, t0,   t0
+  xor   t4, zero, zero
+  xor   t4, zero, t0
+  xor   t4, t0,   t0
+  
+  beq   t0, t0, branch_eq
+  j branch_eq_nt
+end:
+  ret
+
+branch_eq_ret:
+  beq   t0, t3, branch_ne
+  j branch_ne_nt
+
+branch_ne_ret:
+  addi sp, sp, -16  # Adjust stack pointer to make space for ra and s0
+  sw ra, 0(sp)      # Save ra to the stack
+  call func
+  lw ra, 0(sp)      # Load ra from the stack
+  addi sp, sp, 16   # Restore stack pointer
+
+  li  t0, 0x00100000 
+  sw  t1, 0(t0)
+  lw  t2, 0(t0)
+
+  j end
+
+
+branch_eq:
+  addi  t5, zero, 1
+  j branch_eq_ret
+
+branch_eq_nt:
+  addi  t5, zero, 2
+  j branch_eq_ret
+
+branch_ne:
+  addi  t5, zero, 3
+  j branch_ne_ret
+
+branch_ne_nt:
+  addi  t5, zero, 4
+  j branch_ne_ret
+
+func:
+  addi  t5, zero, 5
+  ret
diff --git a/prog/src/prog.s.bak b/prog/src/prog.s.bak
deleted file mode 100644
index 63026c9..0000000
--- a/prog/src/prog.s.bak
+++ /dev/null
@@ -1,99 +0,0 @@
-.section .text
-.globl _start
-
-_start:
-
- 
- j test_prog
-
-
-
-/*
-  addi t0, zero, 31
-reset_loop:
-  addi t6, zero, 0
-loop:
-  addi t6, t6, 1
-  beq t6, t0, reset_loop
-  j loop
-*/
-
-halt_loop:
-  j halt_loop
-
-test_prog:
-  li t0, 0xFFFFFFFF
-  li t1, 0x33333333
-  li t2, 0x88888888
-  li t3, 0x11111111
-
-  add   t4, t1,   t2
-  sub   t4, t1,   t2
-  slt   t4, t3,   t0
-  slt   t4, t0,   t3
-  sltu  t4, t3,   t0
-  sltu  t4, t0,   t3
-  and   t4, zero, zero
-  and   t4, zero, t0
-  and   t4, t0,   t0
-  or    t4, zero, zero
-  or    t4, zero, t0
-  or    t4, t0,   t0
-  xor   t4, zero, zero
-  xor   t4, zero, t0
-  xor   t4, t0,   t0
-  
-  beq   t0, t0, branch_eq
-  j branch_eq_nt
-
-branch_eq_ret:
-  beq   t0, t3, branch_ne
-  j branch_ne_nt
-
-branch_ne_ret:
-  call func
-
-  li  t0, 0x00100000 
-  sw  t1, 0(t0)
-  lw  t2, 0(t0)
-
-  j halt_loop
-
-
-branch_eq:
-  addi  t5, zero, 1
-  j branch_eq_ret
-
-branch_eq_nt:
-  addi  t5, zero, 2
-  j branch_eq_ret
-
-branch_ne:
-  addi  t5, zero, 3
-  j branch_ne_ret
-
-branch_ne_nt:
-  addi  t5, zero, 4
-  j branch_ne_ret
-
-func:
-  addi  t5, zero, 5
-  ret
-
-
-
-
-
-
-
-
-
- 
-.section .data
-
-
-.section .bss
-
-.section .stack
-  .space 0x1000  # Allocate stack space
-stack_top:
-- 
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