![]() I would greatly appreciate any guidance or insights you can provide on resolving these issues. Main Program Code: The main program is as follows:Ĭall 0100 calling the procedure at IP=100 Procedure Code: Below is the procedure I've created, which crashes at the 3rd line, if I'm not mistaken:.Any suggestions on how to overcome this issue would be valuable. The procedure should not exceed 37 bytes, and I need help verifying the correctness of the procedure, which I implemented as a simple bubble sort.Moreover, during the execution of the program using the t command(trace ) step by step, it breaks at the 3rd iteration of the loop, forcing me to redo all the work from scratch. Additionally, I'm tasked with writing a near procedure named 'sort' that performs an ascending sort of signed data in the data segment starting at the address 04F1:0200. Assembly Coding Project: My project involves using the debugger to display the assembly code of the calling program stored in main memory from the address 04F2:0125 to 04F2:0134 (completed).Any insights into why this might be happening would be greatly appreciated. ), it gets stuck at a specific instruction randomly and doesn't proceed to print the next one. Debug Command 'R' Stuck Issue: Sometimes, when I use the 'R' command to view the next instruction (cs:ip.Since this learning method is somewhat unconventional, and there is a lack of documentation, I'm reaching out for assistance with a couple of issues: And as such, I cant really scroll in the output logs, which isnt too convenient. Compiled with all the good flags (either normal or heavy) but I cant seem to get it in its own window : the debugger always opens in my console - and somehow messes it once dosbox is closed. However, a few years ago when I wrote Ur-Scheme, I did do this for lambda expressions: the code for the lambda expression is generated inline in the middle of its containing code, which then has to contain a jump past it.I'm currently facing challenges while working with the debug emulator for assembly coding as part of a course requirement. Im running dosbox(-staging) and Im trying to launch debugger. data, so that if your compiler does this, you still don't have to insert JMP instructions. Gas lets you switch back and forth between. You can also imagine that a compiler might be somewhat simpler if it generated code in the order in which it encountered the expressions. ![]() Maybe someone had this habit in their assembly and adapted it to the 8086's calling convention by inserting MOVs and a JMP instruction? Rather than, say, mov $3, %rdi mov $4, %rsi call atan2. It seems sort of intuitive to do things this way if you're writing atan2(3, 4), it's nice to be able to translate this to Mark Smotherman explains this in more detail, using PDP-8-compatible syntax, in. ![]() So the code to call FOO with arguments 1 and 2 would be (in Intel syntax) So, the callee would indirect from the "return address" stored in FOO to retrieve its arguments, incrementing the return address after each one. They would put them after the JMS instruction in the caller. I was surprised when he told me how people normally passed arguments. So to return, the called subroutine would do an indirect jump using the address stored in the memory word before the beginning of its code. The PDP-8 didn't have a stack to call a subroutine, the JMS FOO instruction would store the return address at (the effective address computed from) FOO, then continue execution at the following word. Thank you for the nice comment!Ī friend of mine used to program the PDP-8 a lot. I have now updated the GitHub repository with this updated source code and binary. Here is a complete example that moves the string to the bottom and saves two bytes: I believe I picked up the style of having the string at the top and jumping over it from other similar code I had come across in those days. Since I was still learning the x86 CPUs, the intention here was not to save bytes but instead to have something working. That chance encounter helped me to dive into the world of assembly language programming much before the coursework introduced me to more popular assemblers. Turned out it was available on any standard installation of MS-DOS as well as Windows 98. While browsing the C:\Windows directory, I fortuitously happened to discover the DEBUG.EXE program. I was still learning microprocessors back then. I happened to stumble upon it today in my archives and thought of sharing it on GitHub. I wrote this about 20 years ago during my university days.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |