Start refactoring instructions.

[fpgaboy.git] / insn_push_reg.v

diff --git a/insn_push_reg.v b/insn_push_reg.v
new file mode 100644 (file)
index 0000000..7a32301
--- /dev/null
+++ b/insn_push_reg.v
@@ -0,0 +1,43 @@
+`ifdef EXECUTE
+       `INSN_PUSH_reg: begin   /* PUSH is 16 cycles! */
+               case (cycle)
+               0:      begin
+                               wr <= 1;
+                               address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
+                               case (opcode[5:4])
+                               `INSN_stack_AF: wdata <= registers[`REG_A];
+                               `INSN_stack_BC: wdata <= registers[`REG_B];
+                               `INSN_stack_DE: wdata <= registers[`REG_D];
+                               `INSN_stack_HL: wdata <= registers[`REG_H];
+                               endcase
+                       end
+               1:      begin
+                               wr <= 1;
+                               address <= {registers[`REG_SPH],registers[`REG_SPL]}-2;
+                               case (opcode[5:4])
+                               `INSN_stack_AF: wdata <= registers[`REG_F];
+                               `INSN_stack_BC: wdata <= registers[`REG_C];
+                               `INSN_stack_DE: wdata <= registers[`REG_E];
+                               `INSN_stack_HL: wdata <= registers[`REG_L];
+                               endcase
+                       end
+               2:      begin /* Twiddle thumbs. */ end
+               3:      begin
+                               `EXEC_NEWCYCLE;
+                               `EXEC_INC_PC;
+                       end
+               endcase
+       end
+`endif
+
+`ifdef WRITEBACK
+       `INSN_PUSH_reg: begin   /* PUSH is 16 cycles! */
+               case (cycle)
+               0:      begin /* type F */ end
+               1:      begin /* type F */ end
+               2:      begin /* type F */ end
+               3:      {registers[`REG_SPH],registers[`REG_SPL]} <=
+                               {registers[`REG_SPH],registers[`REG_SPL]} - 2;
+               endcase
+       end
+`endif