Fix bugs in SCF and CCF

[fpgaboy.git] / core / insn_alu_a.v

diff --git a/core/insn_alu_a.v b/core/insn_alu_a.v
index 14ccd76aae620ee90b99b6d54a463859e24d12af..5fbadeef6ad0c1ae1904a51c6aae8e6799c49f1c 100644 (file)
--- a/core/insn_alu_a.v
+++ b/core/insn_alu_a.v
@@ -9,6 +9,18 @@
 
 `define INSN_ALU_A             9'b000xxx111
 
+`ifdef LOCALWIRES
+       /* Y U Q */
+       /* Derived from MESS opc_main.h */
+       wire [8:0] daa_tmp_n0_h = ((`_F & `FLAG_H) || (`_A[3:0] > 9)) ? {1'b0,`_A} + 9'h06 : {1'b0,`_A};
+       wire [8:0] daa_tmp_n0 = ((`_F & `FLAG_C) || (daa_tmp_n0_h[8:4] > 9)) ? daa_tmp_n0_h + 9'h60 : daa_tmp_n0_h;
+       
+       wire [8:0] daa_tmp_n_h1 = (`_F & `FLAG_H) ? ({1'b0,`_A} - 9'h06) : {1'b0,`_A};
+       wire [8:0] daa_tmp_n_h2 = ((`_F & `FLAG_H) && !(`_F & `FLAG_C)) ? {1'b0,daa_tmp_n_h1[7:0]} : daa_tmp_n_h1;
+       wire [8:0] daa_tmp_n = (`_F & `FLAG_C) ? (daa_tmp_n_h2 - 9'h60) : daa_tmp_n_h2;
+       wire [8:0] daa_tmp = (`_F & `FLAG_N) ? daa_tmp_n : daa_tmp_n0;
+`endif
+
 `ifdef EXECUTE
        `INSN_ALU_A: begin
                `EXEC_NEWCYCLE
@@ -32,18 +44,27 @@
                        `_F <= {`_F[7:5],`_A[7],`_F[3:0]};
                end
                `INSN_alu_RRA: begin
-                       `_A <= {`_A[4],`_A[7:1]};
+                       `_A <= {`_F[4],`_A[7:1]};
                        `_F <= {`_F[7:5],`_A[0],`_F[3:0]};
                end
+               `INSN_alu_DAA: begin
+                       `_A <= daa_tmp[7:0];
+                       `_F <= {
+                                       (daa_tmp[7:0] == 0) ? 1'b1 : 8'b0, /* Z */
+                                       2'b00, /* NH */
+                                       daa_tmp[8], /* C */
+                                       `_F[3:0]
+                               };
+               end
                `INSN_alu_CPL: begin
                        `_A <= ~`_A;
                        `_F <= {`_F[7],1'b1,1'b1,`_F[4:0]};
                end
                `INSN_alu_SCF: begin
-                       `_F <= {`_F[7:5],1'b1,`_F[3:0]};
+                       `_F <= {`_F[7],3'b001,`_F[3:0]};
                end
                `INSN_alu_CCF: begin
-                       `_F <= {`_F[7:5],~`_F[4],`_F[3:0]};
+                       `_F <= {`_F[7],2'b00,~`_F[4],`_F[3:0]};
                end
                endcase
        end