tailieunhanh - Software Solution for Engineers and Scientist Episode 3

Tham khảo tài liệu 'software solution for engineers and scientist episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 154 Chapter 7 ADD CL CL Double number to get shift count SHL DX CL Shift mask bits left AND BX DX Mask off all other tag bits SHR BX CL Shift unmasked tag bits right move message to caller s buffer and exit At this po int BX holds the tag code MOV AX BX Tag code to AX The value in AX is multipl ied by 8 to obtain the offset of the cor res ponding tag code text message Message is then moved to the caller s buffer by DS DI LEA ESI TAG_MESS _TBL Offset of table MOV CL 8 Length of each message MUL CL AX - offset of correct message ADD ESI EAX Add to table offset At this po int ESI - 8-byte number type message EDI - caller s buffer with 8 bytes minimum space MOV ECX 8 Counter for 8 bytes TRANSFER_8 MOV AL ESI Get message character MOV EDI AL Place in caller s buffer INC ESI Bump buffer pointers INC EDI LOOP TRANSFER_8 End of proces sing CLD RET _GET_TAG ENDP SOFTWARE ON-LINE The GET_TAG procedure is found in the Un32_4 module of the MATH32 library in the book s on-line software. The contents of the Stack Top register can be determined more precisely using the FXAM or FTST instructions and interpreting the resulting condition code bits as described in Section . Instruction and Data Pointers The Instruction and Data Pointer registers are part of the math unit environment see Figure . These two registers are jointly called the exception pointers. After each floating-point instruction is executed the math unit automatically saves its operation code and address as well as the operand s address if one was contained in the instruction. This data which is saved internally in the math unit can be examined by storing the environment in memory. The operation of saving and inspecting the environment is shown in the GET_TAG procedure listed previously. The information provided by the instruction and the data pointers is often used by exception handler routines to identify the instruction that generated an error. Math UnitArchitecture and Instruction Set 155 In the 80287 .

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.