From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Fri, 23 Jan 2009 12:37:25 +0000 (-0500)
Subject: Execute: Fix carry flag on subtraction operations.
X-Git-Url: http://git.joshuawise.com/firearm.git/commitdiff_plain/1bc060d94b6e0978c8bdf85795506ab4ed921225?hp=a02d953fd172f2a0ba14a30116d6cdc4885ef4e1

Execute: Fix carry flag on subtraction operations.
---

diff --git a/Execute.v b/Execute.v
index 289ffbb..ac446aa 100644
--- a/Execute.v
+++ b/Execute.v
@@ -291,11 +291,13 @@ module ALU(
 		end
 		`ALU_SUB: begin
 			{flag_c, result} = diff;
+			flag_c = !flag_c;
 			flag_v = diff_v;
 			setres = 1'b1;
 		end
 		`ALU_RSB: begin
 			{flag_c, result} = rdiff;
+			flag_c = !flag_c;
 			flag_v = rdiff_v;
 			setres = 1'b1;
 		end
@@ -311,11 +313,13 @@ module ALU(
 		end
 		`ALU_SBC: begin
 			{flag_c, result} = diff - {32'b0, (~cpsr[`CPSR_C])};
+			flag_c = !flag_c;
 			flag_v = diff_v | (diff[31] & ~result[31]);
 			setres = 1'b1;
 		end
 		`ALU_RSC: begin
 			{flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])};
+			flag_c = !flag_c;
 			flag_v = rdiff_v | (rdiff[31] & ~result[31]);
 			setres = 1'b1;
 		end
@@ -331,6 +335,7 @@ module ALU(
 		end
 		`ALU_CMP: begin
 			{flag_c, result} = diff;
+			flag_c = !flag_c;
 			flag_v = diff_v;
 			setres = 1'b0;
 		end