From 793482e95432866affeec1c87c4d9e94caed8934 Mon Sep 17 00:00:00 2001 From: Christopher Lu Date: Sun, 4 Jan 2009 23:31:10 -0500 Subject: [PATCH] fixed v flag --- Execute.v | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/Execute.v b/Execute.v index ea6cd60..3a21968 100644 --- a/Execute.v +++ b/Execute.v @@ -179,7 +179,6 @@ module Multiplier( end endmodule -/* XXX is the interface correct? */ module ALU( input clk, input Nrst, /* XXX not used yet */ @@ -198,12 +197,15 @@ module ALU( wire [31:0] res; wire flag_n, flag_z, flag_c, flag_v, setres; wire [32:0] sum, diff, rdiff; + wire sum_v, diff_v, rdiff_v; assign sum = {1'b0, in0} + {1'b0, in1}; assign diff = {1'b0, in0} - {1'b0, in1}; assign rdiff = {1'b0, in1} + {1'b0, in0}; + assign sum_v = (in0[31] ^~ in1[31]) & (sum[31] ^ in0[31]); + assign diff_v = (in0[31] ^ in1[31]) & (diff[31] ^ in0[31]); + assign rdiff_v = (in0[31] ^ in1[31]) & (rdiff[31] ^ in1[31]); - /* TODO XXX flag_v not set correctly */ always @(*) begin res = 32'hxxxxxxxx; setres = 1'bx; @@ -222,26 +224,32 @@ module ALU( end `ALU_SUB: begin {flag_c, result} = diff; + flag_v = diff_v; setres = 1'b1; end `ALU_RSB: begin {flag_c, result} = rdiff; + flag_v = rdiff_v; setres = 1'b1; end `ALU_ADD: begin {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b1; end `ALU_ADC: begin {flag_c, result} = sum + {32'b0, cpsr[`CPSR_C]}; + flag_v = sum_v | (~sum[31] & result[31]); setres = 1'b1; end `ALU_SBC: begin {flag_c, result} = diff - {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_v = rdiff_v | (rdiff[31] & ~result[31]); setres = 1'b1; end `ALU_TST: begin @@ -256,10 +264,12 @@ module ALU( end `ALU_CMP: begin {flag_c, result} = diff; + flag_v = diff_v; setres = 1'b0; end `ALU_CMN: begin {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b0; end `ALU_ORR: begin -- 2.19.1