WEBVTT 00:00.500 --> 00:06.950 Hello, my name is Typhoon and in this lecture we are going to write our Makefile to compile this program. 00:06.950 --> 00:12.890 Also we will get again as we did in the previous lecture, we will get the move that or output move 00:12.890 --> 00:16.400 that lStm and move that um M as well. 00:16.400 --> 00:20.390 And I will also produce the move executable move file. 00:20.690 --> 00:25.930 Um, well, so here what we're going to do is we will first go to, um. 00:27.020 --> 00:28.430 Assembly here. 00:28.550 --> 00:30.650 We have the Move project here. 00:31.380 --> 00:32.430 Um, as you can see. 00:32.460 --> 00:35.250 Oops, move, uh, clear here. 00:35.250 --> 00:37.550 So we have moved that here. 00:37.560 --> 00:42.030 What we're going to do is we will open our some text editors in this case. 00:42.030 --> 00:45.240 We also cannot convert gedit or mousepad. 00:45.270 --> 00:53.550 Yes, it depends on is here and we will create something named make file and that's it here. 00:53.730 --> 01:00.990 So what we're going to do is we will need to, uh, right, right here with move, start writing with 01:00.990 --> 01:01.860 move here. 01:02.010 --> 01:06.750 We will first create a move that all this line defines a rule in the make file. 01:06.750 --> 01:11.310 It states that the target move depends on the file move.org. 01:11.340 --> 01:16.350 So this means that if move that all is modified or doesn't exist. 01:16.350 --> 01:22.170 Um, then the target moves rebuilt using this comment here. 01:22.170 --> 01:26.010 And also, uh, we will. 01:26.700 --> 01:29.910 At GCC or move. 01:30.650 --> 01:35.010 But also we will use the no pi here, which I will explain right now. 01:35.030 --> 01:44.450 So this this command is used to link the object file, move that or into the executable named move here. 01:45.170 --> 01:51.440 So it uses the GCC compiler and this all here specifies the output file name. 01:51.440 --> 01:59.450 And this no Pi is a linker option that disables position independent executable in this case pi generation. 01:59.450 --> 02:06.260 So Pi is a security feature that randomizes the address space of the executable, but it's being disabled 02:06.260 --> 02:08.360 here because we want to debug it. 02:08.540 --> 02:15.110 So here we will also add the move.org here. 02:15.500 --> 02:17.660 Now we will move that ESM. 02:19.480 --> 02:23.140 So this line defines the another rule in the make file. 02:23.910 --> 02:29.700 It indicates that the target moved at all depends on the file moved at RSM. 02:29.730 --> 02:38.040 So if we move that RSM is modified or doesn't exist, the target moved at all needs to be rebuilt using 02:38.040 --> 02:39.300 this command here. 02:39.300 --> 02:48.900 Nasm f elf 64 g Move that SM or move that over here and move that LST. 02:48.930 --> 02:56.040 So this command assembles the assembly file, move that RSM using the Nasm here. 02:56.040 --> 02:56.970 Elf 64. 02:57.000 --> 03:00.540 Now let's break the down options and arguments here. 03:00.540 --> 03:06.960 So F Elf 64 specifies the output format to be Elf 64. 03:07.200 --> 03:14.820 The G here generates a debugging information which can be useful for debugging with tools like GDB or 03:15.390 --> 03:16.110 here. 03:16.110 --> 03:24.580 And this move that RSM this is a source assembly file to be assembled and not this all move that all 03:24.580 --> 03:32.260 here specifies the output file name as moveto and L here This is the generates a listing file containing 03:32.260 --> 03:39.130 the assembly code along with the memory addresses so the this listing can be helpful for reviewing reviewing 03:39.130 --> 03:40.990 the assembly code as well. 03:40.990 --> 03:48.010 So to summarize the provide a set of commands and rules as are part of the make file which is used automate 03:48.010 --> 03:50.620 the build process for an assembler program. 03:50.620 --> 03:57.190 So the make file defines how the executable move is built from the assembly source file and move that 03:57.220 --> 04:06.260 RSM by by assembling it into an object file, move that over here and then linking it to g C. 04:06.670 --> 04:13.210 So now what we're going to do is we will save this file right now here and we will continue. 04:14.110 --> 04:20.590 On drawing or on starting out and debugging or JC here. 04:20.680 --> 04:22.380 So now, uh, here. 04:22.390 --> 04:23.290 Clear. 04:23.390 --> 04:29.890 So, cat make file and as you can see, make file is written here and here. 04:29.890 --> 04:33.450 Now we will just press write make, and that's it. 04:33.460 --> 04:35.020 Our program is compiled. 04:35.020 --> 04:38.230 And as you can see, we have this executable file here. 04:38.230 --> 04:43.560 So if we run this and as you can see, we have no output because we are working in a memory. 04:43.570 --> 04:47.230 So now, uh, we saved, uh, the source file. 04:47.230 --> 04:48.850 Yes, everything is okay. 04:48.850 --> 04:53.330 And here we will need to start a triple D, so I will call it D. 04:54.800 --> 04:56.320 The DVD here. 04:56.690 --> 04:57.410 Move. 04:57.530 --> 04:58.700 And that's it. 04:59.210 --> 05:03.860 We installed DDT in actual dribbled is more easy to pronounce. 05:03.860 --> 05:05.070 So I use I. 05:05.090 --> 05:10.160 We installed a triple D in previous lectures, so we will not install it again. 05:10.910 --> 05:17.320 And here we have some informations on blah blah blah here and that's it. 05:17.330 --> 05:23.720 So here you will see this graphical user interface with a rather dated layout. 05:23.720 --> 05:30.590 And DDT is an old open source tool and apparently nobody is willing to adapt it to the graphical user 05:30.590 --> 05:32.780 interface standards we are used today. 05:32.780 --> 05:40.460 And so you have a window with your source file, source code displayed and window where you can type 05:40.880 --> 05:43.370 gdb, gdb command. 05:43.370 --> 05:48.560 So there is also a floating panel where you can click run here. 05:49.300 --> 05:50.510 And see, here we are. 05:50.530 --> 05:51.340 This is the terminal. 05:51.340 --> 05:59.440 We can type GDB commands and if we click on the service menu and um, let's actually click on the source, 05:59.440 --> 06:00.670 uh, menu and. 06:01.430 --> 06:01.940 Um. 06:03.940 --> 06:04.510 Here. 06:04.540 --> 06:06.820 Uh, as you can see here, uh, menu. 06:06.820 --> 06:08.350 And we can, uh, display. 06:08.710 --> 06:09.730 Display. 06:09.730 --> 06:11.320 Uh, line numbers. 06:15.390 --> 06:15.930 Here for. 06:16.020 --> 06:23.100 As you can see here, we have find find words only find case sensitive only line numbers, display machine 06:23.100 --> 06:24.600 code in the source and so on. 06:24.600 --> 06:27.000 So we will click on display line numbers. 06:27.090 --> 06:35.810 Um, we can see the line numbers on the left like the most the new text editors and in the same menu 06:35.820 --> 06:41.100 can choose have a window with the assembled code as well. 06:41.100 --> 06:49.440 So now, uh, we will place the cursor here on this, uh, main and we will right click here. 06:50.630 --> 06:56.840 And here, as you can see here, we will actually let's actually place run here. 06:57.800 --> 07:01.460 And here we can in right click on it. 07:02.480 --> 07:03.530 Now, uh, here. 07:03.530 --> 07:06.590 We can also set the breakpoint here. 07:12.940 --> 07:24.790 Also we now we if we run this again and this, you can see we're one breakpoint main at that in 15 line. 07:25.980 --> 07:26.790 And. 07:28.290 --> 07:29.220 Here. 07:29.610 --> 07:32.250 Uh, let's actually right click on the again. 07:33.030 --> 07:36.090 And as you can see, we have also commands program. 07:37.800 --> 07:38.640 Cool here. 07:38.640 --> 07:40.410 Edit on. 07:50.210 --> 07:54.590 And here again, delete this breakpoint. 07:55.560 --> 07:56.190 Sable. 07:56.190 --> 07:58.470 You can also delete and disable the breakpoints. 07:58.470 --> 08:01.710 But here in this case, let's actually delete again and I will. 08:01.830 --> 08:03.120 Let's run it again. 08:03.120 --> 08:10.800 So what we're going to see is and what we are need to see is we will need to see registers, which this 08:10.800 --> 08:12.930 is the whole logic of this code. 08:12.930 --> 08:19.620 That's why we written this code to show something on registers, uh, which now we will add the main, 08:19.620 --> 08:22.530 uh, main the breakpoint at the main here. 08:23.290 --> 08:32.170 And to observe and understand how the content of registers changes with the this move command, we will 08:32.170 --> 08:32.810 follow. 08:33.200 --> 08:40.900 We need to place the cursor in the front of the main here and we right click on it. 08:43.300 --> 08:46.060 And now we will choose a break. 08:47.080 --> 08:49.790 Or you can also click the. 08:49.840 --> 08:52.780 Yes, uh, you can also click break here on. 08:53.630 --> 08:54.440 It's on break. 08:55.320 --> 08:56.040 And. 08:57.310 --> 09:04.840 Or you can also click on the top of this menu, uh, on the, uh, stop icon here, as you can see here. 09:06.710 --> 09:07.850 But it's right. 09:07.970 --> 09:09.770 Just right click on it and choose break. 09:09.770 --> 09:16.220 And then we will click on Run here on the floating panel debugging. 09:16.250 --> 09:18.620 So this will start a debugging process. 09:18.620 --> 09:25.400 And now we will click on the status here in the top menu bar and then select registers. 09:25.400 --> 09:31.370 So this action will open a window displaying the current values of registers here. 09:32.830 --> 09:33.290 Here. 09:38.310 --> 09:39.120 Make it a little. 09:43.150 --> 09:43.630 But will. 09:44.520 --> 09:45.280 To our screens. 09:45.290 --> 09:47.090 Oh, this is so wide here. 09:47.470 --> 09:47.850 Don't need. 09:53.140 --> 09:55.720 This debugger needs to be updated at. 09:56.500 --> 09:57.760 Graphical here. 09:57.850 --> 09:58.930 But this. 10:23.590 --> 10:25.590 And that's it here. 10:25.600 --> 10:26.410 So. 10:27.820 --> 10:36.640 And after that we will click on this step here to execute the current instruction in the program. 10:41.130 --> 10:41.580 This. 10:48.600 --> 10:49.620 And see here. 10:50.420 --> 10:51.260 Up in. 10:54.770 --> 10:56.060 And here. 10:57.970 --> 11:01.090 As you click this step, you will observe. 11:01.210 --> 11:07.300 You will able to observe how the values in registers change with each step through the program. 11:07.570 --> 11:17.050 If you wish to inspect memory addresses like you num1 or be num, uh, you can uh, go to the view option 11:17.050 --> 11:17.710 here. 11:18.570 --> 11:23.580 And to make the data window visible here and under this data. 11:26.630 --> 11:27.320 But now it's. 11:28.980 --> 11:29.160 I'll. 11:30.810 --> 11:31.230 Was this. 11:31.230 --> 11:32.310 No, we don't want to close this. 11:32.310 --> 11:35.460 I don't want to do it again from zero here. 11:35.460 --> 11:36.600 Let's actually make it. 11:38.280 --> 11:39.000 Down here. 11:39.690 --> 11:41.530 And here, um. 11:42.000 --> 11:45.000 Under here and go from here. 11:45.750 --> 11:46.010 Step. 11:48.460 --> 11:49.030 Here. 11:49.840 --> 11:51.850 Up and up. 11:52.370 --> 11:53.080 Finish. 11:54.480 --> 11:55.260 Interrupt. 11:56.360 --> 11:56.730 That's it. 11:56.750 --> 11:58.190 Now we will run it again. 12:01.730 --> 12:02.900 And here. 12:06.330 --> 12:06.690 You. 12:07.740 --> 12:08.610 Data window. 12:12.230 --> 12:12.680 Even though. 12:21.440 --> 12:24.560 And here, as you can see here, we are seeing our variables as well. 12:25.230 --> 12:28.380 But the most important thing here is in registers. 12:28.500 --> 12:30.540 So and keep in mind that. 12:31.610 --> 12:32.270 Here. 12:32.880 --> 12:36.120 Keep in mind that the while has a graphical interface. 12:36.120 --> 12:44.140 It can sometimes be intricate to navigate, so if you find it faster you can use gdb which is uh, this. 12:44.220 --> 12:52.290 GDB is better, which is and gdb input window for better for certain tasks. 12:52.290 --> 12:58.020 And it's important to keep in mind that DVD is built up on top of gdb. 12:58.440 --> 13:04.710 The new debugger and consequently using a proper function, prologue and epilogue code is essential 13:04.710 --> 13:11.520 to avoid potential uses during the program execution and typically ignores the function prologue while 13:11.520 --> 13:14.820 stepping with the code here. 13:14.970 --> 13:21.840 And the primary objective of this code is to demonstrate how the move command actually again, I want 13:21.840 --> 13:25.950 to do it again here how this move command. 13:28.380 --> 13:32.220 Here impacts the contents of registers. 13:32.220 --> 13:32.850 Right. 13:33.770 --> 13:35.210 As you can see, in racks. 13:35.960 --> 13:38.420 You're always changing the here. 13:40.410 --> 13:41.150 Now see here. 13:41.160 --> 13:44.340 Now it's one, two, three, four, five, six. 13:45.100 --> 13:45.520 An. 13:46.640 --> 13:48.220 It's done because there's a. 13:50.020 --> 13:52.810 Its program is at the read here. 13:52.810 --> 13:55.830 So interrupt it, run it again. 13:55.840 --> 14:00.580 And as you can see, Rex is something just random thing here. 14:00.970 --> 14:06.190 But and in this here we are filling Rex with once. 14:07.270 --> 14:10.510 And here we are. 14:10.510 --> 14:11.110 Step. 14:13.050 --> 14:13.530 Here. 14:13.830 --> 14:20.220 And as you can see here, here now, Rex has the correct value here, which is zero for now. 14:20.220 --> 14:22.650 And here we are filling Rex with ones. 14:22.650 --> 14:30.720 And as you can see, here is the Rex value is one, two, three step again minus one as it did here. 14:30.930 --> 14:37.110 Then again, minus five, 319, one step again and zero again. 14:37.110 --> 14:43.530 So now let's step again and one, two, three, four, five, six, which is the value of our. 14:44.470 --> 14:45.880 Welcome here. 14:48.010 --> 14:48.670 One, two. 14:49.610 --> 14:49.830 We? 14:49.910 --> 14:50.330 Yes. 14:53.160 --> 14:54.090 Again, minus one. 14:54.090 --> 14:56.340 And here we also. 14:59.390 --> 15:00.050 Again. 15:01.130 --> 15:03.230 And no one here. 15:04.320 --> 15:05.430 And after that. 15:06.750 --> 15:13.590 Lastly, we are seeing this move Racks Keenum 123456 here. 15:14.200 --> 15:18.280 And here we are, instruction for floating point number. 15:20.060 --> 15:21.740 And that's it. 15:23.670 --> 15:30.720 So this is, um, how have you, as you continue stepping through the code, you will notice that when 15:30.720 --> 15:38.650 you move a 32 bit value into a 64 bit, register the higher bits in the 64 bit registers are cleared. 15:38.670 --> 15:45.300 So likewise, when you move value in to ax the upper bits of Rax are cleared. 15:45.390 --> 15:51.870 Well, so this insight is vital to keep in mind during programming and debugging.