# HG changeset patch
# User František Kučera <franta-hg@frantovo.cz>
# Date 1513962598 -3600
# Node ID 4b4fb847d01ae33471c494c7142c8251f7602706
# Parent  2ab3d728224939e046005869b5616dfa3fdd8481
GOTO_COMPARE

diff -r 2ab3d7282249 -r 4b4fb847d01a c++/rgb-assembler/rgb-assembler.cpp
--- a/c++/rgb-assembler/rgb-assembler.cpp	Fri Dec 22 17:15:15 2017 +0100
+++ b/c++/rgb-assembler/rgb-assembler.cpp	Fri Dec 22 18:09:58 2017 +0100
@@ -27,6 +27,16 @@
 const command_t CMD_GOTO = 0x70;
 
 /**
+ * Compare values on two addresses and go to one of given three addresses.
+ * parameter: address_t a
+ * parameter: address_t b
+ * parameter: address_t GOTO target when a == b
+ * parameter: address_t GOTO target when a > b
+ * parameter: address_t GOTO target when a < b
+ */
+const command_t CMD_GOTO_COMPARE = 0x80;
+
+/**
  * Wait given time in ms.
  * parameter: sleep_t
  */
@@ -64,6 +74,8 @@
  */
 const command_t CMD_INVALID = 0x1;
 
+// TODO: more commands, better numbers
+
 /**
  * Reads data on given position in memory and increments the index (position).
  */
@@ -101,7 +113,7 @@
 		write<command_t>(memory, a, CMD_SLEEP);
 		write<sleep_t>(memory, a, 255);
 		write<command_t>(memory, a, CMD_GOTO);
-		write<address_t>(memory, a, a + 4);
+		write<address_t>(memory, a, a + sizeof (address_t) + 2 * sizeof (command_t));
 		write<command_t>(memory, a, CMD_INVALID);
 		write<command_t>(memory, a, CMD_INVALID);
 		write<command_t>(memory, a, CMD_SLEEP);
@@ -115,6 +127,12 @@
 		write<address_t>(memory, a, 0);
 		write<command_t>(memory, a, CMD_DECREMENT);
 		write<address_t>(memory, a, 0);
+		write<command_t>(memory, a, CMD_GOTO_COMPARE);
+		write<address_t>(memory, a, 0);
+		write<address_t>(memory, a, 0 + sizeof (command_t) + sizeof (sleep_t));
+		write<address_t>(memory, a, a - 3 * sizeof (address_t) - 2 * sizeof (command_t));
+		write<address_t>(memory, a, 0);
+		write<address_t>(memory, a, a + sizeof (address_t));
 		write<command_t>(memory, a, CMD_END);
 	}
 
@@ -158,6 +176,27 @@
 				wprintf(L"%sCREMENT %*d → %02X\n", (ch == CMD_INCREMENT ? "IN" : "DE"), 5, address, value);
 				break;
 			}
+			case CMD_GOTO_COMPARE:
+			{
+				address_t aa = read<address_t>(memory, i);
+				address_t ab = read<address_t>(memory, i);
+				address_t eq = read<address_t>(memory, i);
+				address_t gt = read<address_t>(memory, i);
+				address_t lt = read<address_t>(memory, i);
+
+				byte_t a = read<byte_t>(memory, aa);
+				byte_t b = read<byte_t>(memory, ab);
+
+				if (a == b) {
+					i = eq;
+				} else if (a > b) {
+					i = gt;
+				} else {
+					i = lt;
+				}
+				wprintf(L"GOTO COMPARE  a = %02X, b = %02X, eq = %d, gt = %d, lt = %d → %d\n", a, b, eq, gt, lt, i);
+				break;
+			}
 			case CMD_END:
 			{
 				wprintf(L"END\n");