From 5b1aee887b7a9dddbecf40d8afb8e1873ee02331 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sergiusz=20=27q3k=27=20Baza=C5=84ski?= <q3k@q3k.org>
Date: Sat, 4 Jan 2014 14:07:57 +0100
Subject: [PATCH] All ALU tests pass

---
 .gitignore    |  1 +
 Makefile      |  2 +-
 cpu.v         |  7 +++++--
 test_main.cpp | 17 +++++++++++++++++
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 1377554..4888c89 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 *.swp
+obj_dir
diff --git a/Makefile b/Makefile
index 63fb6dc..f9295d3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 obj_dir/Vcpu.cpp: cpu.v test_main.cpp
 	verilator -Wall -cc cpu.v --exe test_main.cpp
 
-obj_dir/Vcpu: obj_dir/Vcpu.cpp
+obj_dir/Vcpu: obj_dir/Vcpu.cpp test_main.cpp
 	cd obj_dir; make -j -f Vcpu.mk Vcpu
 
 test: obj_dir/Vcpu
diff --git a/cpu.v b/cpu.v
index f64538f..97cfcbe 100644
--- a/cpu.v
+++ b/cpu.v
@@ -187,8 +187,11 @@ module cpu (
                     vr[15] <= {7'b0, vr[x][0]};
                     vr[x] <= vr[x] >> 1;
                 end
-                7: { vr[15], vr[x] } <= ({8'b0, vr[y]} - {8'b0, vr[x]}) ^ (1 << 8);
-                15: begin
+                7: begin
+                    vr[x] <= vr[y] - vr[x];
+                    vr[15] <= {7'b0, vr[y] >= vr[x]};
+                end
+                14: begin
                     vr[15] <= {7'b0, vr[x][7]};
                     vr[x] <= vr[x] << 1;
                 end
diff --git a/test_main.cpp b/test_main.cpp
index 7963f4e..82e1a78 100644
--- a/test_main.cpp
+++ b/test_main.cpp
@@ -99,4 +99,21 @@ int main(int argc, char **argv)
     test_alu_instruction_vf(0x45, 0x45, 0x8125, 0x00, 0x01);
     printf("SUB (borrow) ");
     test_alu_instruction_vf(0x15, 0x45, 0x8125, 0xD0, 0x00);
+    // SHR
+    printf("SHR (one) ");
+    test_alu_instruction_vf(0x45, 0x00, 0x8126, 0x45>>1, 0x01); 
+    printf("SHR (zero) ");
+    test_alu_instruction_vf(0x44, 0x00, 0x8126, 0x44>>1, 0x00);
+    // SUBN
+    printf("SUBN (no borrow) ");
+    test_alu_instruction_vf(0x15, 0x45, 0x8127, 0x30, 0x01);
+    printf("SUBN (zero, no borrow) ");
+    test_alu_instruction_vf(0x45, 0x45, 0x8127, 0x00, 0x01);
+    printf("SUBN (borrow) ");
+    test_alu_instruction_vf(0x45, 0x15, 0x8127, 0xD0, 0x00);
+    // SHL
+    printf("SHL (one) ");
+    test_alu_instruction_vf(0xA4, 0x00, 0x812E, (0xA4<<1)&0xFF, 0x01);
+    printf("SHL (zero) ");
+    test_alu_instruction_vf(0x24, 0x00, 0x812E, (0x24<<1)&0xFF, 0x00);
 }