Execute: Fix carry flag on subtraction operations.

[firearm.git] / Execute.v

diff --git a/Execute.v b/Execute.v
index 289ffbb649d7b652d721fd48e59398b76cbea09f..ac446aafffc6d88fb73554b61716e2433717527b 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -291,11 +291,13 @@ module ALU(
                end
                `ALU_SUB: begin
                        {flag_c, result} = diff;
                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_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
                        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])};
                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_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
                        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;
                end
                `ALU_CMP: begin
                        {flag_c, result} = diff;

+                       flag_c = !flag_c;

                        flag_v = diff_v;
                        setres = 1'b0;
                end
                        flag_v = diff_v;
                        setres = 1'b0;
                end