chapter4.7-mikroprocessor
Post on 20-Jun-2015
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Data Movement Instructions
A Course in Microprocessor
Electrical Engineering Department
University of Indonesia
Assembler Detail Directives
– Some common assembly language directives (pseudo-operations) appear in Table 4.21
– Directives indicate how an operand or section of program is to be processed by the assembler:
• Storing Data in a Memory Segment: DB, DW, DD, SEGMENT, .DATA, ENDS, DUP, ALIGN -ex.4.12
• ASSUME, EQU, ORG: the EQU equates a numeric, ASCII, or LABEL to another label -ex.4.13; the THIS refers the data as byte or word -ex.4.14; the ORG (origin) changes the starting offset address of data in the data segment; the ASSUME tells the
Assembler Detail (cont’d)
the assembler what names have been chosen for the code, data, extra, and stack segments; the PROC and ENDP indicate the start and end of a procedure (subroutine) -ex.4.15; others are CALLF, CALLN, RETF, RETN, NEAR, FAR -ex.4.16
Memory Organization– The assembler uses two basic formats for deve-loping
software: models and full-segment defi-nitions (available to the MASM assembler)
– Models (ex.4.17): The TINY model (64 KB) and the SMALL model (128 KB), and HUGE model (>128 KB)
Assembler Detail (cont’d)
Full Segment Definitions– Ex.4.18 & Ex.4.19 illustrate the use of full-
segment definitions• Full-segment definitions are also used with the
Borland and Microsoft C/C++ environments for procedures developed in assembly language
– More structured form than the model method– STACK_SEG, DAT_SEG, CODE_SEG, END
MAIN
Assembler Detail (cont’d)
A Sample Program– Study carefully Ex.4.20
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