From 142510b8325b9ef89bd3e22463f36c3caa2815de Mon Sep 17 00:00:00 2001
From: Flavian Kaufmann <flavian@flaviankaufmann.ch>
Date: Mon, 20 May 2024 12:18:20 +0200
Subject: io

---
 prog/link.ld       |  8 ++++----
 prog/src/main.c    |  8 ++++----
 prog/src/startup.s | 17 +++++++++++++++++
 src/io.v           |  6 ++++--
 src/top.v          |  2 +-
 5 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/prog/link.ld b/prog/link.ld
index 7bd11eb..9644d59 100644
--- a/prog/link.ld
+++ b/prog/link.ld
@@ -3,8 +3,8 @@
 /* Define memory regions */
 MEMORY
 {
-    ROM (rx)  : ORIGIN = 0x00010000, LENGTH = 0x400  /* 1024 bytes for ROM */
-    RAM (rwx) : ORIGIN = 0x00100000, LENGTH = 0x400  /* 1024 bytes for RAM */
+    ROM (rx)  : ORIGIN = 0x00010000, LENGTH = 0x1000  /* 1024 bytes for ROM */
+    RAM (rwx) : ORIGIN = 0x00100000, LENGTH = 0x1000  /* 1024 bytes for RAM */
 }
 
 ENTRY(_start)
@@ -43,7 +43,7 @@ SECTIONS
     .stack (NOLOAD) :
     {
         _stack_start = .;
-        . += 0x80; /* Adjust the size as needed */
+        . += 0x100; /* Adjust the size as needed */
         _stack_end = .;
     } > RAM
 
@@ -51,7 +51,7 @@ SECTIONS
     .heap (NOLOAD) :
     {
         _heap_start = .;
-        . += 0x80; /* Adjust the size as needed */
+        . += 0x100; /* Adjust the size as needed */
         _heap_end = .;
     } > RAM
 }
diff --git a/prog/src/main.c b/prog/src/main.c
index 62b802b..082172d 100644
--- a/prog/src/main.c
+++ b/prog/src/main.c
@@ -1,13 +1,13 @@
 #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) {
-  *io_out = 0;
   while (1) {
     for (int i = 0; i < 32; ++i) {
-      *io_out = i;
+      *((volatile uint32_t *)0x00000004) = i;
+      for (int j = 0; j < 1024 * 128; ++j);
     }
   }
 }
diff --git a/prog/src/startup.s b/prog/src/startup.s
index 7adfb5e..963c288 100644
--- a/prog/src/startup.s
+++ b/prog/src/startup.s
@@ -1,6 +1,23 @@
 .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
 
diff --git a/src/io.v b/src/io.v
index f062f31..f53062b 100644
--- a/src/io.v
+++ b/src/io.v
@@ -14,15 +14,17 @@ module io (
 
 `include "include/consts.vh"
 
-always @ (posedge clk) begin
+always @ (posedge clk or negedge rstn) begin
   if (!rstn) begin
     io_out <= 32'b0;
   end else if (we && addr == 32'h0000_0004) begin
     io_out <= wd;
   end
+end
+
+always @ (posedge clk) begin
   if      (addr == 32'h0000_0000) rd <= io_in;
   else if (addr == 32'h0000_0004) rd <= io_out;
   else                            rd <= 32'b0;
 end
-
 endmodule
\ No newline at end of file
diff --git a/src/top.v b/src/top.v
index 86f26ce..fc1d9fe 100644
--- a/src/top.v
+++ b/src/top.v
@@ -10,7 +10,7 @@ assign rstn = key;
 wire [31:0] io_in;
 wire [31:0] io_out;
 
-clock_divider #(.N(1024 * 1024)) clkdiv (
+clock_divider #(.N(1)) clkdiv (
     .clk(clk),
     .rstn(rstn),
     .clk_div(clk_cpu)
-- 
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