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These are the user uploaded subtitles that are being translated: 1 00:00:00.05 --> 00:00:01.04 - [Instructor] We've already seen 2 00:00:01.04 --> 00:00:03.09 a couple of simple programs in Assembler, 3 00:00:03.09 --> 00:00:05.08 so let's look at their structure. 4 00:00:05.08 --> 00:00:07.05 In our first MASM program, 5 00:00:07.05 --> 00:00:09.07 we can see that we start with an include file 6 00:00:09.07 --> 00:00:11.07 from the MASM32 folder. 7 00:00:11.07 --> 00:00:14.01 Let's see what this looks like. 8 00:00:14.01 --> 00:00:17.00 The file we've included starts after its initial comments 9 00:00:17.00 --> 00:00:20.05 by setting some key MASM configuration items. 10 00:00:20.05 --> 00:00:23.05 At line 32, we can see the library specifies 11 00:00:23.05 --> 00:00:25.05 a 486 architecture, 12 00:00:25.05 --> 00:00:28.09 which sets the assembler up for 32 bit code. 13 00:00:28.09 --> 00:00:31.09 It uses the flat 32 bit addressing memory model 14 00:00:31.09 --> 00:00:34.06 and establishes case sensitivity. 15 00:00:34.06 --> 00:00:39.01 It then brings in a set of include files 16 00:00:39.01 --> 00:00:42.01 and their corresponding libraries for Windows 17 00:00:42.01 --> 00:00:43.05 so that we're ready to make calls 18 00:00:43.05 --> 00:00:47.01 to the Windows application programming interface, 19 00:00:47.01 --> 00:00:49.00 Note that we have include statements 20 00:00:49.00 --> 00:00:53.06 for kernel32.lib and user32.lib. 21 00:00:53.06 --> 00:00:55.09 The next thing we see in our MASM program 22 00:00:55.09 --> 00:00:58.08 is that our code is divided into two sections. 23 00:00:58.08 --> 00:01:03.00 The first starting at line two with a .data declaration 24 00:01:03.00 --> 00:01:07.01 and the second starting at line four with .code. 25 00:01:07.01 --> 00:01:09.05 At line five, we have the start label 26 00:01:09.05 --> 00:01:10.04 and at line eight, 27 00:01:10.04 --> 00:01:11.06 the end start statement identifies 28 00:01:11.06 --> 00:01:16.03 start as the entry point for the program. 29 00:01:16.03 --> 00:01:18.06 So the basic structure for a program 30 00:01:18.06 --> 00:01:21.01 is to set up the processor and memory model 31 00:01:21.01 --> 00:01:22.09 and bring in any external files, 32 00:01:22.09 --> 00:01:28.02 which in this case we do by including masm32rt.inc, 33 00:01:28.02 --> 00:01:30.09 define data in a .data segment, 34 00:01:30.09 --> 00:01:33.08 define code in the .code segment, 35 00:01:33.08 --> 00:01:37.03 and then end the program with the name of the entry point. 36 00:01:37.03 --> 00:01:41.04 Let's close the project 37 00:01:41.04 --> 00:01:44.06 and select File, New Project. 38 00:01:44.06 --> 00:01:49.04 We'll again, make it a MASM project 39 00:01:49.04 --> 00:01:52.01 and the classic console application. 40 00:01:52.01 --> 00:01:57.01 And we'll take the default name. 41 00:01:57.01 --> 00:01:59.08 Easy Code has provided a program skeleton for us. 42 00:01:59.08 --> 00:02:03.02 This has a couple of extra sections that we didn't use. 43 00:02:03.02 --> 00:02:06.06 The .Const section is used to declare Constance. 44 00:02:06.06 --> 00:02:09.00 This allows us to have a named constant 45 00:02:09.00 --> 00:02:11.08 rather than just using the value in our code. 46 00:02:11.08 --> 00:02:16.08 For instance, we could add a line, answer 47 00:02:16.08 --> 00:02:18.08 EQU 48 00:02:18.08 --> 00:02:20.03 42, 49 00:02:20.03 --> 00:02:24.00 and note that you can also use equal sign instead of EQU, 50 00:02:24.00 --> 00:02:30.02 and then at line 18, we can put in mov, 51 00:02:30.02 --> 00:02:33.07 eax comma, 52 00:02:33.07 --> 00:02:35.03 answer. 53 00:02:35.03 --> 00:02:38.07 If we select Build, Compile Project1, 54 00:02:38.07 --> 00:02:41.07 it assembles just fine. 55 00:02:41.07 --> 00:02:44.08 The data question mark section at line five 56 00:02:44.08 --> 00:02:46.03 is used to declare variables 57 00:02:46.03 --> 00:02:48.04 that we don't need to initialize. 58 00:02:48.04 --> 00:02:51.05 This saves a significant amount of space in the program 59 00:02:51.05 --> 00:02:55.07 by not having to carry a pre-initialized data area. 60 00:02:55.07 --> 00:02:58.08 The skeleton is designed to allow us to use the Windows API 61 00:02:58.08 --> 00:03:02.08 and so starts by making a call at line 13 62 00:03:02.08 --> 00:03:04.07 to get module handle, 63 00:03:04.07 --> 00:03:06.07 which returns a handle to the program itself 64 00:03:06.07 --> 00:03:09.00 in the register Eax. 65 00:03:09.00 --> 00:03:11.04 This is then stored in hinst 66 00:03:11.04 --> 00:03:15.03 so that we can use it when we need to during our coding. 67 00:03:15.03 --> 00:03:17.07 The skeleton code uses an exit process 68 00:03:17.07 --> 00:03:20.06 as the preferred method of closing down the program 69 00:03:20.06 --> 00:03:23.01 which also ensures any attached DLLs 70 00:03:23.01 --> 00:03:25.02 are properly closed down. 71 00:03:25.02 --> 00:03:27.06 Setting zero on the exit process 72 00:03:27.06 --> 00:03:31.07 indicates that the program is exiting with no errors. 73 00:03:31.07 --> 00:03:36.08 Okay, I'll close this project. 74 00:03:36.08 --> 00:03:39.04 We'll not be focusing on the intricacies of creating 75 00:03:39.04 --> 00:03:42.07 fully featured Windows GUI programs in Assembler, 76 00:03:42.07 --> 00:03:45.02 but let's see what the program skeleton looks like 77 00:03:45.02 --> 00:03:48.06 when we do elect to build a standard Windows executable. 78 00:03:48.06 --> 00:03:54.00 We'll select File, New Project, 79 00:03:54.00 --> 00:03:59.07 and we'll select a MASM Windows executable. 80 00:03:59.07 --> 00:04:07.01 MASM Windows executable file. 81 00:04:07.01 --> 00:04:09.07 The program skeleton is somewhat more complicated 82 00:04:09.07 --> 00:04:14.05 as this provides the code necessary to create a window. 83 00:04:14.05 --> 00:04:16.03 Note in particular that at line 18 84 00:04:16.03 --> 00:04:18.05 it invokes to get command line 85 00:04:18.05 --> 00:04:20.08 and then invokes its own WinMain function 86 00:04:20.08 --> 00:04:23.03 which appears further down. 87 00:04:23.03 --> 00:04:26.04 We'll learn more about Windows calls later in the course. 6876