tailieunhanh - linux assembly language programming PHẦN 10

Mẹo h trong tên chức năng đề cập đến "chủ nhà", trong khi n đề cập đến "mạng". Tương tự như vậy, s là "ngắn" và l đề cập đến "dài." Sử dụng các công ước, nó là một vấn đề đơn giản để chọn tên của chức năng chuyển đổi bạn xem lại mã nguồn của bạn để làm cho nó hoạt động. | uv IHiO pviiil. JWVVVi IV U-HV 1UVVV ƯVgiHUU Ui UOOH HUi OV 1VHUIIH H WUH l umuuv segmentation. Segmentation in protected mode is discussed in chapter 13 section . Real Mode Segmentation The terms segment and segmentation are used in many overlapping and conflicting ways. Consequently it would be well to make a preliminary attempt at clarifying terminology. In DOS code and data segments of a program may be stored in code and data segments of memory but aren t necessarily. In Linux they never are. Text and data segments of a program are stored on separate pages of memory not separate segments of memory. In x86 Lrnnx the error message SegmentationFauIt doesnot refer to a segmentation fault it refers a page protection fault. Worst of all is the term logical segment which accurately specifies nothing at all. To avoid wantonly muddying things further this book will doggedly adhere to the following distinctions between program segments memory segments and segmentation. Segments and Segmentation Program segment. Since chapter 8 we have applied the term segment to a chunk of an executable file. This is standard usage. Programs typically have text and data segments. Segmentation process. In this book the term segmentation is applied only to an address processing mechanism which has the effect of dividing memory into chunks. Memory segment. It is customary to apply the term segment to the chunks of memory produced by the segmentation process. In this book memory segments will always be referred to in connection with a special kind of register called segment register. On an x86 processor segmentation is controlled by segment registers. Segment Registers On the 8086 four of the general registers can be used for addresses BX BP SI and DI. That is they can be used in brackets to refer to memory. For example the commands MOV BX 1234H MOV AL BX would copy the contents of one memory location into the AL register. But BX BP SI and DI are 16-bit registers and the 8086