X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/f2b745a710572fd5cb2b1cf97d1d05a9b74d4fe1..f9000d73c8971e2e6323122efb06bcfd846b5d62:/insn_ldm_a.v

diff --git a/insn_ldm_a.v b/insn_ldm_a.v
new file mode 100644
index 0000000..485b6a4
--- /dev/null
+++ b/insn_ldm_a.v
@@ -0,0 +1,43 @@
+// If opcode[4], then ld A, x, else ld x, A
+// If opcode[1], then ld 16m8, else ld 8m8
+
+`ifdef EXECUTE
+	`INSN_LDM_A: begin
+		case (cycle)
+		0:	begin
+				`EXEC_INC_PC
+				`EXEC_READ(`_PC + 16'h0001)
+			end
+		1:	begin
+				`EXEC_INC_PC			// we only hit here if 16m8
+				`EXEC_READ(`_PC + 16'h0001)
+			end
+		2:	if (opcode[4])	// LD A,x
+				`EXEC_READ(({tmp, tmp2}))
+			else
+				`EXEC_WRITE(({tmp, tmp2}), `_A)
+		3:	begin
+				`EXEC_NEWCYCLE
+				`EXEC_INC_PC
+			end
+		endcase
+	end
+`endif
+
+`ifdef WRITEBACK
+	`INSN_LDM_A: begin
+		case (cycle)
+		0:	if (!opcode[1]) begin
+				tmp <= 8'hFF;
+				cycle <= 1;	/* Skip cycle 1 */
+			end
+		1:	tmp2 <= rdata;
+		2:	if (opcode[1])
+				tmp2 <= rdata;
+			else
+				tmp <= rdata; 
+		3:	if (opcode[4]) `_A <= rdata;
+		endcase
+	end
+`endif
+