Say ABCD.
[fpgaboy.git] / insn_ret-retcc.v
index ef89003..bad4c04 100644 (file)
@@ -1,30 +1,20 @@
 `ifdef EXECUTE
        `INSN_RET,`INSN_RETCC: begin
                case (cycle)
-               0:      begin
-                               rd <= 1;
-                               address <= {registers[`REG_SPH],registers[`REG_SPL]};
-                       end
+               0:      `EXEC_READ(`_SP)
                1:      begin   // SPECIAL CASE: cycle does NOT increase linearly with ret!
-                               `EXEC_INC_PC;   // cycle 1 is skipped if we are not retcc
+                               `EXEC_INC_PC    // cycle 1 is skipped if we are not retcc
                                case (opcode[4:3])
-                               `INSN_cc_NZ:    if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
-                               `INSN_cc_Z:             if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
-                               `INSN_cc_NC:    if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
-                               `INSN_cc_C:             if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
+                               `INSN_cc_NZ:    if (registers[`REG_F][7]) `EXEC_NEWCYCLE
+                               `INSN_cc_Z:     if (~registers[`REG_F][7]) `EXEC_NEWCYCLE
+                               `INSN_cc_NC:    if (registers[`REG_F][4]) `EXEC_NEWCYCLE
+                               `INSN_cc_C:     if (~registers[`REG_F][4]) `EXEC_NEWCYCLE
                                endcase
-                               rd <= 1;
-                               address <= {registers[`REG_SPH],registers[`REG_SPL]};
-                       end
-               2:      begin
-                               rd <= 1;
-                               address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1;
+                               `EXEC_READ(`_SP)        // retry the read
                        end
+               2:      `EXEC_READ(`_SP + 1)
                3:      begin /* twiddle thumbs */ end
-               4:      begin
-                               `EXEC_NEWCYCLE;
-                               // do NOT increment PC!
-                       end
+               4:      `EXEC_NEWCYCLE
                endcase
        end
 `endif
                0:      if (opcode[0])  // i.e., not RETCC
                                cycle <= 1;     // Skip cycle 1; it gets incremented on the next round.
                1:      begin /* Nothing need happen here. */ end
-               2:      registers[`REG_PCL] <= rdata;
-               3:      registers[`REG_PCH] <= rdata;
+               2:      `_PCL <= rdata;
+               3:      `_PCH <= rdata;
                4:      begin
-                               {registers[`REG_SPH],registers[`REG_SPL]} <=
-                                       {registers[`REG_SPH],registers[`REG_SPL]} + 2;
+                               `_SP <= `_SP + 2;
                                if (opcode[4] && opcode[0])     /* RETI */
                                        ie <= 1;
                        end
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