WEBVTT 00:01.080 --> 00:04.410 Now let's discuss how we can use some registries. 00:05.280 --> 00:09.990 Let's begin by creating a new file called Sub Registers Got Nazim. 00:16.890 --> 00:27.720 And as usual, let's start with our global director of Global Space and let's start and let's specify 00:27.720 --> 00:28.810 our entry point here. 00:29.850 --> 00:33.480 Now, once again, we are going to use the move instructions. 00:33.750 --> 00:42.060 But instead of using a register like Oryx and RDX, we are going to try to use the sobre histories of 00:42.060 --> 00:43.050 those registers. 00:43.440 --> 00:44.820 So let's get started. 00:45.330 --> 00:50.910 The first let's use move el chromatin. 00:52.020 --> 00:54.480 This is one of the protesters from Artex. 00:55.920 --> 01:00.390 Let's also use more Aage Qamar, 20. 01:02.010 --> 01:05.660 Let's also use move AICS. 01:06.880 --> 01:21.090 Come on, 30, let's use more eggs, comma 100, finally, let's use more our eggs, comma 200. 01:21.760 --> 01:27.520 If you notice, we have used pretty much every register from the area register. 01:28.180 --> 01:34.810 This is just to demonstrate that we do not have to use the full 64 bit register if you just want to 01:34.810 --> 01:37.220 store some smaller value into a register. 01:37.600 --> 01:43.180 So let's save the file and let's use Nazem to assemble this program. 01:43.660 --> 01:50.090 Nazem SPACEHAB registers not Nazan Dash for some registers darte. 01:50.120 --> 01:54.670 Oh once again the format is going to be ELV 64. 01:55.090 --> 01:55.930 Let's render. 01:58.400 --> 02:08.000 Now, let's link it using Ellie and leastways, sub registers that all space dash for sub registers. 02:08.450 --> 02:11.740 Let's enter now like we did earlier. 02:11.870 --> 02:14.230 Let's open up this program using Jollibee. 02:14.710 --> 02:17.960 So I'm typing GDP space sub registers. 02:19.220 --> 02:26.570 And let's once again set up a breakpoint at the beginning of the program, which is underscore start 02:27.530 --> 02:31.870 and let us run the program once again. 02:31.970 --> 02:37.490 If you notice, we have zero eight, which is being moved into L Register. 02:37.850 --> 02:44.600 Ultimately, even if you are moving it into L register, it is going to be saved in order to register 02:45.020 --> 02:48.770 because L is a sub register from Addicks. 02:49.100 --> 02:54.250 So let's quickly check what we have in Attic's register before executing this instruction. 02:54.950 --> 03:02.930 If you notice, currently Attic's register contains the value of zero, so let's type inside and let's 03:02.930 --> 03:04.430 see what happens. 03:05.780 --> 03:10.250 Dirigo IREX register now contains the value zero x a. 03:11.690 --> 03:19.070 Now let's try to execute the next instruction which is moving Heggs 14 into the register h. 03:20.060 --> 03:21.440 I'm hitting enter once again. 03:24.170 --> 03:24.740 And. 03:26.560 --> 03:34.480 Look at that now, age condemns the value 14 and L contains the value zero error, and both of them 03:34.480 --> 03:36.640 together are forming this value. 03:37.240 --> 03:42.330 Now let's move zero x one E into X register. 03:42.880 --> 03:49.390 So I'm typing aside once again, if the previous command that you have typed is a site you don't have 03:49.390 --> 03:52.210 to assign, once again, you can just hit enter. 03:52.360 --> 03:55.410 It is just going to take, say, from the previous command. 03:55.690 --> 04:01.360 So I'm hitting enter without typing anything so that it will do a single step automatically for me. 04:01.690 --> 04:02.560 I'm hitting enter. 04:04.070 --> 04:11.840 Now, the value Hecks money should have been moved into the Register X. Let's go at once again. 04:13.830 --> 04:22.530 Look at that zero one, he's now moved into the Register X. Now the next instruction to be executed 04:22.530 --> 04:29.750 is move the value hex 64 into X, which is the same 100. 04:30.180 --> 04:36.990 So let's go and let's observe IREX once again. 04:37.020 --> 04:39.800 As you can see, we have x 64. 04:41.460 --> 04:46.530 Finally, we are moving a decimal 200 into X register once again. 04:46.530 --> 04:50.610 If you notice, when we were writing this program, we used our X register. 04:50.880 --> 04:56.890 But Assembler has made some optimizations and the auto register is not used. 04:57.340 --> 05:00.780 Instead, the sample register X is used here. 05:01.200 --> 05:08.450 So let's say once again and let's examine how to register. 05:08.460 --> 05:13.780 As you can see, the value Heggs C8 is morphed into an X register. 05:14.250 --> 05:16.900 So this is how we can use some registers. 05:17.310 --> 05:21.750 Now, there is one interesting thing to note about when we are using some registers. 05:22.200 --> 05:33.330 Let me quit GDP and let type object down and let's dump the disassembly of the program that we have 05:33.330 --> 05:41.040 just written, which is some registers and let type dash m in there so that the instructions will be 05:41.040 --> 05:42.900 shown in internal syntax. 05:43.350 --> 05:46.740 OK, so let's hit enter and look at that. 05:47.350 --> 05:55.140 If you notice the instructions which are having the registers like X and are X with smaller values are 05:55.140 --> 05:57.850 having null bytes in the disassembly. 05:58.510 --> 06:03.840 However, when we used a sub registers, they did not produce any null bytes. 06:04.380 --> 06:09.480 So making use of some registers is a great way to avoid null bytes. 06:09.480 --> 06:14.750 When writing Schenkkan, we are going to discuss these concepts once again when we write code. 06:15.060 --> 06:20.930 But since we came across the concepts of using some registers, I just wanted to quickly show you this. 06:21.360 --> 06:21.760 All right. 06:21.870 --> 06:23.400 So that's all for this video. 06:23.610 --> 06:24.720 See you in the next one.