![Irvine, Kip R. Assembly Language for x86 Processors 6/e, 2010.
9
Instructions
Instructions
• Assembled into machine code by assembler
• Executed at runtime by the CPU
• We use the Intel IA-32 instruction set
• An instruction contains:
• Label (optional)
• Mnemonic (required)
• Operand (depends on the instruction)
• Comment (optional)
[Label:] Mnemonic Operand(s) [; Comment]](https://image.slidesharecdn.com/chap3intro-241003100519-11634a13/85/chap3intro-ppt-assembly-language-fundamentals-9-320.jpg)
chap3intro.ppt(assembly language fundamentals)
- 1. Assembly Language for x86 Processors Assembly Language for x86 Processors 7th Edition 7th Edition Chapter 3: Assembly Language Fundamentals Kip Irvine
- 2. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 2 Chapter Overview Chapter Overview • Basic Elements of Assembly Language • Example: Adding and Subtracting Integers • Assembling, Linking, and Running Programs • Defining Data • Symbolic Constants • 64-Bit Programming
- 3. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 3 Basic Elements of Assembly Language Basic Elements of Assembly Language • Integer constants • Integer expressions • Character and string constants • Reserved words and identifiers • Directives and instructions • Labels • Mnemonics and Operands • Comments • Examples
- 4. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 4 Integer Constants Integer Constants • Optional leading + or – sign • binary, decimal, hexadecimal, or octal digits • Common radix characters: • h – hexadecimal • d – decimal • b – binary • r – encoded real Examples: 30d, 6Ah, 42, 1101b Hexadecimal beginning with letter: 0A5h
- 5. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 5 Integer Expressions Integer Expressions • Operators and precedence levels: • Examples:
- 6. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 6 Character and String Constants Character and String Constants • Enclose character in single or double quotes • 'A', "x" • ASCII character = 1 byte • Enclose strings in single or double quotes • "ABC" • 'xyz' • Each character occupies a single byte • Embedded quotes: • 'Say "Goodnight," Gracie'
- 7. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 7 Reserved Words and Identifiers Reserved Words and Identifiers • Reserved words cannot be used as identifiers • Instruction mnemonics, directives, type attributes, operators, predefined symbols • See MASM reference in Appendix A • Microsoft Macro Assembler Reference • Identifiers • 1-247 characters, including digits • not case sensitive • first character must be a letter, _, @, ?, or $
- 8. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 8 Directives Directives • Commands that are recognized and acted upon by the assembler • Not part of the Intel instruction set • Used to declare code, data areas, select memory model, declare procedures, etc. • not case sensitive • Different assemblers have different directives • NASM not the same as MASM, for example
- 9. Irvine, Kip R. Assembly Language for x86 Processors 6/e, 2010. 9 Instructions Instructions • Assembled into machine code by assembler • Executed at runtime by the CPU • We use the Intel IA-32 instruction set • An instruction contains: • Label (optional) • Mnemonic (required) • Operand (depends on the instruction) • Comment (optional) [Label:] Mnemonic Operand(s) [; Comment]
- 10. Irvine, Kip R. Assembly Language for x86 Processors 7/e, 2015. 10 Labels Labels • Act as place markers • marks the address (offset) of code and data • Follow identifer rules • Data label • must be unique • example: myArray (not followed by colon) • Code label • target of jump and loop instructions • example: L1: (followed by colon)