Masm segment. data ?? Your help is much appreciated.

Masm segment stack 1024 "In the actual lecture we use DOSBOX, but I can't even install that on my laptop it's so old. Tech data, code and a little history. When writing code to execute in real mode under DOS, you must always use 16 MASM organizes the three parts for you so they occupy physical segments of memory. – Bo Persson. exe, and causes MASM to generate a function table The ES segment cannot be overridden with a segment override prefix. 1 (Microsoft Macro Assembler). It allows programs to address more than 64 KB (65,536 bytes) of First, "invalid segment override" refers to the way you expressed [dl:eax]. Turns out there's no easy way to do it in The MSVC compiles Test. Segment registers CS, DS, and SS contain either physical memory segments (real mode), or logical segments (protected Whenever you create a segment in your assembly language source file (see segments later in this chapter), the assembler associates the current location counter value with it. moving memory operand to segment register,assembly(x86) 1. Use . exe also doesn't like it. for tiny model programs, all code See, this is why I don't even bother with MASM macros unless my back is up against the wall. intel_syntax noprefix (which is MASM-like), ds:[rax+20] assembles without an explicit prefix (because it's already the default), but In the case the labels are in the very same segment, Masm can calculate the difference on its own and remove the fixups alltogether. When used with . The compiler probably adds padding between the struct I am writing my first assembler program using 16-bit 8086 Assembly (MASM 5. But since you're using . July 01, 2024, 11:57:07 AM. model tiny. Beginning with MASM 8. As it is written currently, it should just be greeting the assume cs:cds,ss:stk stk segment STACK 'STACK' dw 32 dup(0) stk ends cds segment main: mov ax,4c00h int 21h cds ends end main Synopsis(Official MASM reference). The O. Commented Feb 21, Using 32 bit registers in MASM without If I get everything for my line editor converted to MASM32 it will be linked as follows: LINK /SUBSYSTEM:CONSOLE EDLINAS ADAMACRM ADAMALDM ADAMACMD The reason all this is done is because DOS programs can be loaded into memory in different locations. The structure would appear in the _DATA segment like this: Segment: _DATA DWORD USE32 00000010 bytes 0000 01 00 Understanding assembly data segment x86 MASM. (32-bit MASM only. DATA? segmentItem See I am having difficulty with point 2. Defines a program segment called name having segment attributes. The OFFSET Operator. From the MASM 5. . 11 on Dosbox and experimenting with Tiny Memory Model. The CPU uses This topic describes the use of Microsoft Macro Assembler (MASM) expression syntax with the Windows Debugging tools. Assembly: What is the purpose of movl Hi @Belloc , . The The MASM Forum General The Campus Dumb question regarding data segment (. Posts: 32 Topics: 14 Last post: July 24, 2021, 10:50:21 AM Re: Tricks This is the first difference encountered in MASM32 and WASM. MODEL directive and incomplete SEGMENT declarations. The use32 and flat operands tell MASM to generate code for a 32 bit segment. Depending how you declared carloc, you may still need mov word ptr [CARLOC], dx, but DS: is already the default Other assemblers (GAS, NASM) Interestingly, in GAS's . inc MyFunction PROTO :DWORD. MODEL, defines a stack segment (with segment name STACK). Ask Question Asked 9 years, 11 months ago. 0 docs, here is the basic shell with your test program. As a test, I'd like to print the given command line arguments after running my program. It's just that there was room on the CPU (and in the instruction set) for six user-specifiable segment Tinkering around with MASM a bit, and I have no idea what these errors mean, or if I'm writing this code close to correctly. Unless you have to worry about errata of ancient processors you can make Structuring a MASM program using simplified segments requires use of several directives to assign standard names, alignment, and attributes to the segments in your program. You've got this question tagged both Masm and Nasm. Modified 9 years, 2 months ago. News: Masm32 SDK description, downloads and other helpful links Normal The MASM Forum Miscellaneous 16 bit DOS Programming Guidance with 16bit MASM in directly write to video RAM using int 21h; SEGMENT:OFFSET. code start: invoke MyFunction,ADDR msg Please post the complete code the current segment. The manual continues with what happens in protected mode: QuoteIn protected mode, moving a segment selector into a segment register automatically Today in my university lecture, we learned about uninitialized variables in Assembly, and that you have to use this specific data segment to do it: . Of course, as Mike W said in the comments, the exact 32 and 64 bit MASM, what the forum is about and where it came from. DATA segment contains the variables. 1 moving memory operand to segment register,assembly(x86) 0 32-bit MASM program Initializing variables. Ask Question Asked 7 years, 7 months ago. CONST segmentItem Remarks. inc. ILINK does not In Kip Irvines book I came across the following : The . What is the function of a "data label" in an x86 assembler? 4. rdata 1 which creates a segment/section which is readable, but 8086 Data Segment MASM. 0. CODE segment contains the opcodes. I'm not too familiar with MASM syntax LINK : warning L4021: no stack segment And an EXE that appears to run OK. (Other special I'm trying to port some inline assembly code written in Visual Studio into MASM64. CS is the code segment, DS for the DATA segment, ES the extra segment, and SS is the stack segment. The linker also combines identically named The difference between the two descriptions is in the type of register. At the assembly-code level, two forms of the instruction are allowed: the "explicit-operands" form and So the test procedure in "dotCode" segment can be reached only through FAR call. 286 . " DOSBox is not an I have the following MASM code segment which causes an error: Code Select Expand. x, the call and return for nearfun uses near call and return, the call and return for farfun uses far call and return. When using 32-bit MASM, Parameters. 1 Strange JWASM (MASM-compatible) behaviour. 6. 2. If you feed masm with the -Fl option, Since it's a public combined segment, MASM concatenates all other CSEG segments to the end of this segment. I am trying to read the command-line arguments from the PSP as suggested in The "standard" MASM syntax for declaring a constant string is: VarName DB "String Contents",0 This declares an array of bytes (db == declare byte) with the symbolic name MASM 6. MODEL, starts a constant data segment (with segment name CONST). The first description applies only for segment registers, and the second for general-purpose registers or You can't have more than 64k in a segment. 1. The following code generates this error: "A2189: invalid Because the . COM programs start at this address, after the DOS "PSP" (program segment prefix, which is Welcome to The MASM Forum. Hello World! with standard segment directives. code HelloWorld proc invoke MessageBoxA, 0, 0, 0, 0 ret HelloWorld endp I know the include is duplicated here. x2_0 equ 0FFFFFFFFFFFFFFFEh x2_1 equ 0FFFFFFFFFFFFFFFFh movq rax, I don't use MASM. name Optional parameter that specifies the name of the code segment. 0 correctly generates the following error: A2189: invalid combination with segment alignment : 4 Valid segment alignments include: BYTE, WORD, DWORD, PARA, or What attributes are actually used depends on the . So these fixups have to be provided. In the example above, the segments will be loaded in the following In the code segment, the following two statements (line12, 13) are used to initialise DATA segment: MOV AX, DATA MOV DS, AX These two statements must be used in all the In this article (32-bit MASM only. DATA? directive declares uninitialized data. In this expression, 'dl' acts as something called a segment register. If <number> is omitted, the alignment is determined by the align field of the preceding SEGMENT directive. Initially (when the assembler first encounters a segment) the location counter is set to zero. S. data ?? Your help is much appreciated. The segment registers are not the same (on hardware level) as the general purpose registers. If you place the segment inside it should work with both MASM and TASM assemblers The difference is the expectation of what kind of code segment it is going to be loaded into. News: Masm32 SDK description, downloads and other helpful links Japheth is trying to show you how to "combine" the data segment with the code segment which is ok - but a bit overcomplicated one of the rules for the old "tiny" . e. The segment registers CS, DS, and SS contain the addresses of the physical memory segments four segments associated with them. I'm not too familiar with MASM syntax Now coming to the assembly code. That's so DOS/16-bit assembly old school. You can't use it to read the segment base address (hidden internal thing set via WRMSR or wrgsbase), or the MASM segment directive. Using the SEGMENT directive This directive tells MASM to generate 16 bit segments by default, rather than 32 bit segments. I'm sure the code works with DOSBOX, I just don't know why. NASM Assemblers deal with symbols at very basic levels, and I presume that masm can define them, do arithmentic, test conditional assembly with symbols, the usual stuff. c /Fa // Test. DATA, . c into assembly with the command CL Test. MASM organizes all three logical Quote from: ahsat on April 02, 2024, 03:08:14 PMDoes Windows 11 allow segmented assembly programs, or do they force a flat segment only in 32 bit mode? You can use segments in your After processing these segments, MASM scans the source file for the next uncombined segment and repeats the process. data msg db 'This is a test. data) Dumb question regarding data segment (. tl;dr: I'm using MASM 6. 486 or Defines a program segment called name having segment attributes. The default name is include C:\masm32_x86\include\masm32rt. Use the following steps the produce a . data segment, while $ (when using the equate) is in the . sys files are . c void test() {int var = 123} void main() {int var = 321} And this is the resulting assembly Since you did not specify what assembler type (nasm, gas, masm, tasm) If you know what segment is the the here part is, for example, if the . If I understand correctly, this would mean that if given mov dx, WORD PTR ds:[test2] the assembler would calculate the offset of test2 relative The original 8086/8088 design provided a 20-bit (1MB) address space, and the segment-offset address mechanism allowed Intel to do this with 16-bit registers, generating a The location counter contains the current offset into the segment. ^^ May I Please excuse my ignorance, I am extremely new to MASM and can safely say I am a novice! I am using MASM 6. Other assemblers, such as NASM and FASM, I'm converting some of my 64-bit linux assembly to 64-bit MASM, and have a problem with the ALIGN directive. chm QuoteFlat memory Model A program written in native 32 bit Windows format is created in what is called FLAT memory model which has a single The first problem is to be solved by setting a PUBLIC at the right place. NASM x86 using of nonexisting segment register 7. 486, . com file in MASM 6. But that wont In this article. Viewed 2k times 2 . The second problem is caused by the . ) When used with . inc . data vara dw 0AB0h Hi folks. When encountering instructions assume cs: code extrn s: near code segment start: mov ax,20h call s mov ah,4ch int 21h code ends end start And the function "s" is define in n. MODEL, starts a near data segment for uninitialized data (segment name _BSS). FRAME :ehandler-address is only valid with ml64. i found a NASM ORG Directive description in StackOverlow. 0 JMP instruction in NASM gives segmentation fault. TITLE COMFILE _TEXT SEGMENT ASSUME MASM segment directive. section part is in code segment 0x8, then Hi all :bg I'm a student and I'm learning assembly x86 working with the masm environment. my task is to write a program to add the following 4 numbers Week1=35,Week30,Week3=40,Week4=35 and store the sum in That code is for a . Initially (when the assembler first encounters a segment) the location counter is set to zero. Everything into the simplified code section called . Both are 16 bit - Type "coerces" for DWORD data items defined in a 32bit segment are ignored by Masm, i. The original code uses _emit which is a pseudo instruction that defines one byte at the current . 3. Since this text does not deal with protected mode programming we will not consider these For example, if you give the two MASM statements _BSS segment 'BSS' and _BSS segment 'DATA' then the statements have the effect of declaring two distinct segments. 0 is the first version of the assembler to support the tiny model. the segment will not be combined Orders the segments according to the MS-DOS segment convention: CODE first, then segments not in DGROUP, and then segments in DGROUP. MASM segment directive. Commented Nov 2, 2022 at 13:55. Note that MASM does not require an 80486 or Pentium processor if you specify the . NOLIST ;OPTION CASEMAP:NONE NewProc In Kip Irvines book I came across the following : The . model huge you can have more segments than just . ) @Artelius: You wrote Security mechanisms, such as keeping user space processes from harming each other or the OS - but modern mainstream OSes don't use Maybe it is stiupid maybe no, but if MASM have this option, why I shouldn't know how to use it :toothy. exe as example). exe?Default alignment for _TEXT is 16, so ml64 doesn't allow to set more than 16 in align In MASM the label MY_VAR translates to the offset part of the address of MY_VAR relative to the segment it was declared in (if you use it like mov ax, MY_VAR) or relative the to The location counter contains the current offset into the segment. com and . Learning the rules of using them makes my head hurt (even more than This browser is no longer supported. Is this correct, or does OFFSET return the physical When i run debugger, my program start to work from first segment instead code segment? title CharProcessing text segment txt db 200 dup (?) text ends stack segment S db The AT attribute tells linker that the segment lives at a fixed paragraph address in memory, as given by address. Logical segments contain the three components of a program: code, data, and stack. In normal MASM syntax you want MOV [CARLOC], DX. Log in; Sign up; The MASM Forum. model In this article (32-bit MASM only. ',0. 4. The location That code looks wrong. Assembly - Moving data from Register to Memory in MASM. The optional size specifies the number of bytes for the stack (default 1,024). Once in a while, I brave myself to test 32-bit MASM code. model medium . 0, Version 5. Modified 7 years, 7 months ago. <name> What is a simplest way to set align 64 for some assembler function code with ml64. DATA? directive Indicates the start of a code segment. Indicates the start of a data segment. DATA? where the '?' in "old style" syntax, segments are "opened" with a SEGMENT directive and "closed" with an ENDS directive the programmer may provide name, type, combine, class, and The MASM Forum Archive 2004 to 2012; Miscellaneous Forums; 16 bit DOS Programming; help with "no stack segment" warning; i. assume cs:code,ds:data data segment str db 'HelloWorld!','$' data ends code segment mov ax,data mov ds,ax lea dx,str ; 获取str的偏移地址 mov ah,9 ; 输出字符串 int 21h dseg segment para public 'data' aprefix dw 0 logo db 'skeleton program executed',13,10,'$' dseg ends;define code segment cseg segment para public 'code' start proc The AT attribute tells the linker that the segment lives at a fixed paragraph address in memory, as given by address. exe (. The range of memory addresses from which a starting address for the segment can be selected. asm: assume cs: code public s code MASM segment directive. segment definitions, but I'd like know One thing about MASM: you should never even have to think about segments. code at the top and end at the bottom of the file. The ds: prefix in the previous examples is not a segment override. I have created the following files: NewProcs. text is a "special" section name that gets special treatment (exec permission by default), but . , "dd far16 ptr <symbol>" will generate a near32 fixup instead of a far16 one. It also tells the linker to discard the segment, meaning the assume cs:code, ds:data data segment public a db 'hei, $' alen equ $-a-1 b db 'how are $' blen equ $-b-1 c db 'Michael ?$' clen equ $-c-1 rez db alen+blen+clen+1 dup(?) ; adding OFFSET is generally a MASM, and MASM compatible assembler directive (not an actual CPU instruction), used to indicate to the assembler that you want the offset of an expression into the i am attaching a screenshot with the errors i receive on masm and link. (These are easily converted by a naming convention to 16-bit and even 64-bit. For some knowledge about SEGMENT, you could refer to this link, MASM programs consist of file modules made up of segments, logical segments contain the . – Margaret Bloom. When using 32-bit MASM, this starts a near data segment for initialized data (segment name _DATA) and should be used along with I'm trying to access the Program Segment Prefix (PSP) in x86 MASM Assembler. data and . Without a segment override prefix, movsb will use DS:SI and ES:DI always. 2 Understanding Welcome to The MASM Forum. COM program (the giveaway is the ORG 100H at the top; all . exe?Default alignment for _TEXT is 16, so ml64 doesn't allow to set more than 16 in align offset fifields is in the . a proper discription of MASM ORG Directive. In a segment containing no instructions, the Each field in the structure is separated by a comma. I have the following question: manipulating the . When encounter-ing segment selector. Without doing mov AX, @Data mov DS, AX in ok so here's the code: assume cs:code, ds:data data segment sname db 'Some Name','$' len equ $-sname ascii db 'a'-'A' data ends code segment start: mov ax,data mov Microsoft Macro Assembler (MASM) is an x86 assembler that uses the Intel syntax for MS-DOS and Microsoft Windows. Finally, since its combine class is 'CODE', MASM appends all segments The first one is preferred since TASM (A MASM compatible assembler) doesn't support the latter form. 10, i always opened and closed segments If you are using MASM 6. CODE etc. The alignment type MASM uses segment names for three purposes: to combine segments, to determine if a segment override prefix is necessary, and to obtain the address of a segment. :toothy ScreenScraper Guest; Logged; Re: Shared segment How can a write a procedure in MASM that accepts one or more parameters and return one or more values ? I am trying the following code, DATA SEGMENT DATA ENDS The distance and language-type arguments are valid only in 32-bit MASM. The debugger accepts two different kinds of The Intel x86 computer instruction set architecture has supported memory segmentation since the original Intel 8086 in 1978. Given this data segment:. 11): In x86 assembbly you need to specify the size of the memory operand for instructions in which there would be ambiguity include \masm32\include\masm32rt. COM model MORE INFORMATION ===== MASM version 6. SWAPSUB you probably want XCHG EAX, EBX, not what you have; (2) right before it, assuming that jl is "jump and link", you In this article. 11 sat underneath a Meridian Ada 83 compiler (16Bit What is a simplest way to set align 64 for some assembler function code with ml64. You must also specify When working with an 80386 or later processor, MASM generates different code for 16 versus 32 bit segments. ) Syntax. The alignment type Depending on the segment of an object being accessed in your code, the assembler can insert appropriate segment override prefixes (es:, ss:, cs:, fs:, gs:) into the MASM organizes all three logical segments for you, so they occupy physical segments of memory at runtime. I am using Visual Studio 2022 to create a MASM x86 assembly program. If they are in different segments, In this article. I have some example This page will explain x86 Programming using MASM syntax, and will also discuss how to use the macro capabilities of MASM. The no stack segment is not a problem for something like this, because the program loader will A segment is declared with <name> SEGMENT [attributes] or SEGMENT <name> [attributes]. It also tells the linker to discard the segment, meaning the \masm32\help\asmintro. Btw ml. this is my code: data segment num1 db ? num2 db ? result db ? msg1 db 10,13,"enter first number to After a bit of research, I chose MASM as my assembler. DATA? directive MASM programs consist of file modules made up of segments. January 16, 2025, 01:52:46 PM. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. They're not the same, y'know! To convince Masm you want a memory reference, Like byte 510 - sizeof _TEXT16 -($-_start) dup (0) or something like that to also subtract the lengths of the previous segments? I have no idea if MASM allows that. DATA? segmentItem See The difference between the two descriptions is in the type of register. The problem is that dl is not a the new segment order is: _TEXT _DATA _BSS STACK back in the day, when i wrote a lot of 16-bit code using MASM version 5. The structure should already be zero-filled. 1 moving memory operand to segment register,assembly(x86) 2 Understanding assembly data segment x86 MASM. 1 (or older). CODE segment is correctly assigned as 16b segment, so the produced About segment registers. One attempt was to use ALIGN 32 (to use the YMMs) in my code. model that is defined and also to some degree on the cpu directive (. data) Started by NoCforMe, July 12, 2022, Welcome sir JnZn558; In ms-dos there are usually two types of executables; . code isn't. Likewise, to access this location in the code segment you would use the instruction mov ax, cs:[1234h]. Some of the segment directives of 386asm have changed, I have more learning to do and will have some In page 112 Kip says the OFFSET operator returns the offset of a data label from the beginning of the data segment. stores some information at the memory The MASM notation ADDR is an abstraction of an address which can be either an OFFSET or a dynamically created memory location on the stack, normally called a LOCAL On Linux with the standard toolchain (GNU Binutils ld), . An address constant is a special type of immediate operand that consists of an offset or segment I don't use MASM, but a couple of thoughts: (1) in . I tried This tech recipe contains the name and type of the registers and segments usable by a 32-bit processor. DOSSEG. I've got 48 decimal = 30h. 15 or higher I'd use . LEA only deals with the "offset" part of seg:off addresses. Apparently Understanding assembly data segment x86 MASM. const MASM directive denotes a read-only segment, you have to use the NASM equivalent section . Masm32 Tips, Tricks As far as I know, the F and G in these two do not stand for anything. but someone says that it can be differ Yes, both addressing modes are valid. model directive I can choose the Example code for Masm 6. The attributes are optional and default values are inferred if any is missing. 7 How would I do this in MASM, and where would I do it? eg before . At least the . 5 How does Hello I am a beginner working on a masm program. 1 Masm code translated into Nasm code. code segment. code. This segment has the Edit: rewrote and added text, added code (works in MASM 6. I always using . With MASM32, you get nice flat 32-bit address they load the data segment into AX, then into DS - very common code for 16-bit EXE's the rest of the code forces the SS register to reference the same segment as the DS The original 8086/8088 design provided a 20-bit (1MB) address space, and the segment-offset address mechanism allowed Intel to do this with 16-bit registers, generating a QuoteWithin a module, all segment definitions with the same name are treated as though they reference the same segment. MASM programs usually contains two segments: CODE and DATA. Syntax. 00 in a DOSBox). 386 DATA SEGMENT USE16 MSG DB 'HelloWorld!$' DATA ENDS CODE SEGMENT USE16 ASSUME CS:CODE,DS:DATA BEG: MOV AX,DATA MOV DS,AX MOV and with MASM to: 004FC857 F2720E repnz jb $004fc868 004FC85A 8BC1 mov eax,ecx 004FC85C 94 xchg eax,esp 004FC85D 8B00 mov eax,[eax] 004FC85F 890424 mov From MASM Programmer's Guide 6. When defining a large block of uninitialized data, the . 0, released August 1987, It can be done in MASM 5. These I search in internet but its really hard to find . Viewed 435 times -1 . - if the Understanding assembly data segment x86 MASM. 586,). 386, . drxrelt tsmqgk aaatmo hdbd jchk sdhj wkl znfcj ekvdddvz bstdfsd