Start refactoring instructions.

[fpgaboy.git] / insn_pop_reg.v

diff --git a/insn_pop_reg.v b/insn_pop_reg.v
new file mode 100644 (file)
index 0000000..9d4acbd
--- /dev/null
+++ b/insn_pop_reg.v
@@ -0,0 +1,44 @@
+`ifdef EXECUTE
+       `INSN_POP_reg: begin    /* POP is 12 cycles! */
+               case (cycle)
+               0:      begin
+                               rd <= 1;
+                               address <= {registers[`REG_SPH],registers[`REG_SPL]};
+                       end
+               1:      begin
+                               rd <= 1;
+                               address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1;
+                       end
+               2:      begin
+                               `EXEC_NEWCYCLE;
+                               `EXEC_INC_PC;
+                       end
+               endcase
+       end
+`endif
+
+`ifdef WRITEBACK
+       `INSN_POP_reg: begin    /* POP is 12 cycles! */
+               case (cycle)
+               0:      begin end
+               1:      begin
+                               case (opcode[5:4])
+                               `INSN_stack_AF: registers[`REG_F] <= rdata;
+                               `INSN_stack_BC: registers[`REG_C] <= rdata;
+                               `INSN_stack_DE: registers[`REG_E] <= rdata;
+                               `INSN_stack_HL: registers[`REG_L] <= rdata;
+                               endcase
+                       end
+               2:      begin
+                               case (opcode[5:4])
+                               `INSN_stack_AF: registers[`REG_A] <= rdata;
+                               `INSN_stack_BC: registers[`REG_B] <= rdata;
+                               `INSN_stack_DE: registers[`REG_D] <= rdata;
+                               `INSN_stack_HL: registers[`REG_H] <= rdata;
+                               endcase
+                               {registers[`REG_SPH],registers[`REG_SPL]} <=
+                                       {registers[`REG_SPH],registers[`REG_SPL]} + 2;
+                       end
+               endcase
+       end
+`endif