Tags down


Segment and offset uses

By : JDavid
Date : July 30 2020, 02:00 AM
it should still fix some issue As mentioned in the comments by Nate Eldredge, the segments overlap. Each subsequent 86 Mode segment starts 16 bytes after the prior one. So (as mentioned) there are 4096 (4 Ki) ways to address any one byte.
The exception is to do with A20 handling on later x86 CPUs. On those, if A20 is enabled, memory in the first 64 KiB has less aliases pointing to it. An address that would "wrap" on the 8086, starting with 0FFFFh:0010h, would have pointed into the first 64 KiB (starting with linear address 00_0000h).
code :

Share : facebook icon twitter icon

get offset and segment address of string

By : sammysheep
Date : March 29 2020, 07:55 AM
hop of those help? Segments and offsets are antiquated features from before protected mode came to x86 chips.
Once they gained protected mode, they started using selectors to get away from the fact that memory addresses were now virtual rather than physical. And they generally use a flat model nowadays, which has very few selectors, each with a large (and sometimes the same) backing memory block.
code :
#include <stdio.h>
int main (void) {
    int xyzzy = 42;
    printf ("Address is %p\n", &xyzzy);
    return 0;

How does the segment:offset addressing scheme work?

By : hainc
Date : March 29 2020, 07:55 AM
it should still fix some issue The segment register value is shifted left by 4 (multiplied by 16) and added to the operand address.
16 * 65536 = 1 megabyte.

access data segment using offset

By : suman ghimire
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further arr1 is an Array of WORDs i.e. 16-bit-values. mov eax,[esi] receives a 32-bit-value in this case two 16-bit-values. So you'll find in EAX the first and the second element of arr1. If you want to fill the whole EAX only with the first value use movzx eax, word ptr [esi] instead. This instruction fills the lower 16 bits of EAX with the element and nullifies the upper 16 bits.

Set stack segment and offset in assembly

By : ZheXing Yang
Date : March 29 2020, 07:55 AM
This might help you I set up 4k stack space begins at end of the bootloader. After that, I read 16 sectors (=8k) of code to address 0x2000:0x0000. It's the kernel of my operating system. And I branched to it. , Try
code :
mov ax,2000h
mov ss,ax
mov sp,4000h

segment:offset in a constant

By : Borkat Rambe
Date : March 29 2020, 07:55 AM
Does that help x86 doesn't have a way to load from an immediate-constant far-pointer in one instruction. There's a far jmp ptr16:16 that can set cs:ip to a 32-bit immediate, but for loads I don't see any option that doesn't use a segment register.
code :
 ;; return in AL (zero-extended to AX; the upper byte of 0040h happens to be 0)
 ;; clobbers: AH, ES
    mov     ax, 0x0040
    mov     es, ax
    mov     al, [es:0x0475]
 ;; return in AL (zero-extended to AX; the upper byte of 0040h happens to be 0)
 ;; clobbers: AH,  or nothing if you uncomment the push/pop of AX
    push    es
    ;push    ax                 ; you might as well use a reg other than AX to simplify this, if you do want to preserve AH, too.  And also for performance on CPUs that don't rename low8 partial regs separately, so mov al,[mem] has a dependency on the pop.
      mov     ax, 0x0040
      mov     es, ax            ; or use DS if you don't need it in any interrupt handler
    ;pop     ax
      mov     al, [es:0x0475]
    pop     es
 ;; return in AL
 ;; requires/assumes: DS=0
    mov     al, [0x0475]
Related Posts Related Posts :
  • How to wait until a job is done or a file is updated in airflow
  • How to copy a Excel column to a Java list
  • Using Tim2 inside interrupt handler for STM32F1
  • Exit Event / Welcome Event Not Firing
  • EXCEL isThisWeek()
  • What does native_write_msr in kernel do?
  • Q Language for usage in KDB
  • Assign std:wstring to VCL UnicodeString most effectively
  • How can I send data via TCP
  • z3 Solver and solve give different results
  • IBM CDC AS400 w/ Encryption
  • Change size from woocommerce PayPal checkout button in cart
  • Will there be a performance overhead when using an index having Object_Pairs (in case of a covered query) - Couchbase
  • How do trigger the key combination 'CTRL+SHIFT+ENTER' using Testcafe .keypress()?
  • Microsoft Azure Refresh Token Expires after 90 days
  • How do I set focus to a text box in Blazor
  • How to supply snakemake options within the Snakefile itself?
  • COPY command skipping files in snowflake
  • How can I query a NCLOB column as a table in SAP HANA?
  • CPP how to escape a quotation mark
  • How to replicate Who bot people search criteria?
  • How CPU predicts, the instruction and data limits in the sequence of binary information of binary file?
  • Set a Single Select control as required in Google Data Studio
  • How to perform polynomial subtraction and division in galois field
  • How to create RPM package that uses setcap and works on both dnf/yum (fedora/redhat) and zypper (openSuse)
  • sympy polynomial roots expressions
  • Include own posts with posts from followed users
  • Manage API to create forests in all nodes in a group in a clustered environment
  • How to expose read-only calculations from business domain model on back-end to front-end using CQRS? A Read-Model vs. Wr
  • How to deploy a Daml smart contract to Hyperledger Fabric or Sawtooth?
  • Does the CouchDB 3.0 8MB limit per document, include the attachments to the document?
  • Show waves in Modelsim with Cocotb
  • System.MissingMethodException: 'Method not found': Error
  • Does MarkLogic support Object.values()?
  • Is there some difference between use Tokens or strings in compiler construction?
  • Defining of time complexity of algorithm(log n or n)
  • Are there alternatives to template literals in Bixby?
  • How to convert variables from version 2 to version 4 of pinescript?
  • Is Vulkan positive X-axis pointing to the right of the screen?
  • How to construct a balanced connector for liquids in Modelica?
  • When to use noEvent operator in Modelica language?
  • How to get loaded monitor color profile with Applescript (or command line)?
  • How to check for DOM .contains? in clojurescript?
  • could not find implicit value for parameter um: akka.http.scaladsl.unmarshalling.FromRequestUnmarshaller[class]
  • How can I use the same randomly generated number twice? - SwiftUI
  • How can I include double quotes in a SWI-PL command line argument?
  • How to upgrade Jfrog Artifactory pro to enterprise or enterprise+?
  • Oracle Apex - refresh all subregions with one refresh in dynamic action
  • How can I return to the login view in a SwiftUI app
  • Gremlin: Get Vertex property keys grouped by parent vertex
  • How to define constraint about consecutive periods in optaplanner
  • Maximo Spatial: Configure text at top left corner of map?
  • Boto3 DynamoDB Query Conditions not working (except for eq)
  • Change color of distribution plot in qlik sense
  • How to count a number on in Elixir without built in function such as Enum.count?
  • Comparision between "cts.values" and "cts.elementValues"
  • Zeppelin alternative for K-V store
  • How to get name of executing stored procedure in Snowflake?
  • Modelica: How to assign an instance of type Child into variable of type Parent?
  • How to build an abstract with a Haxe macro?
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org