16-bit

I am going through some example assembly code for 16-bit real mode. I've come across the lines: mov bx, cs mov ds, bx mov si, OFFSET value1 pop es mov di, OFFSET value2 what is this doing? What does having 'OFFSET' there do? Nathan Fellman As some of the other answers say, the offset keyword refers to the offset from the segment in which it is defined. Note, however, that segments may overlap and the offset in one segment may be different in another segment. For instance, suppose you have the following segment in real mode data SEGMENT USE16 ;# at segment 0200h, linear address 2000h org 0100h

I have an embedded 16 bit CPU. On this machine ints are 16 bit wide and it supports longs that are 32 bits wide. I need to do some multiplications that will need to be stored in 64 bits (e.g. multiply a 32 bit number by a 16 bit number). How can I do that with the given constraints? I do not have a math library to do this. Just another metaprogrammer A suggestion in C. Note that this code probably will be easier to implement with inline assembler as carry detection in C doesn't seem that easy // Change the typedefs to what your compiler expects typedef unsigned __int16 uint16 ; typedef

I am writing a bootloader in assembly and it seems to work fine on qemu, bochs and virtualbox. However, it is not loading the kernel on real hardware (it seems). The bootloader starts off by writing a character to the video memory (for debugging), it then reads sector 2 off the drive and far jumps to the kernel. The kernel is then writing some characters to video memory. On a real machine, I see the character from the bootloader on the screen, and there it hangs (blinking caret). I have tried to set DS, ES, SI to zero, and I am also setting up a stack segment. I am reading sector 2 off of the

I am looking to display heightmaps from the video game Battlefield 2 as images in my application. I am new to C++ and Qt and it might be straight forward but what I am having trouble with is displaying a grayscale 16-bit 1025x1025 2101250 bytes image. There is no header to the file. I need access to the displayed pixels (does not have to be pixel perfect precision) so I can point to a pixel and get its value. What I have tried I have loaded the binary data into a QByteArray from a QFile and I have attempted to use the QImage::fromData function to make the image but I am making a lot of

I'm trying to understand GAS's behavior of .code16. From the manual, it seems in 16-bit section, for 32-bit operands or instructions, a 66H operand override prefix will be produced for the instruction encoding. Does that mean .code16 movw %eax, %ebx is legal in such mode? Then the code cannot run on 16-bit processor? Dirk Wolfgang Glomp These are legal instructions for 80386+. Starting with the 80386 we can use operandsize- and addresssize- override prefixes. Those prefixes can be used in combination with the 16 bit address mode and with the 32 bit address mode. Additional it can be used with