Assembly Language Basic Concepts IA32 Processor Architecture Hardware

Assembly Language Basic Concepts IA-32 Processor Architecture

Hardware Intel 386, Intel 486, Pentium, or latest processors, AMD processors, or compatible processors. The same architectures, but different organizations. ¡ Not working in MAC computers, SUN Sparc workstations. ¡

Operating Systems MS-DOS, Windows 95/98/ME/NT/2000/XP. ¡ Advanced programs relating to direct hardware access and disk sector programming must be run under MS-DOS, Windows 95/98/ME. ¡ Not working in Linux, MAC OS. ¡

Programming Software Editor: Microsoft Visual C++, Text. Pad, Notepad. ¡ Assembler and linker: MASM 6. 15. ¡ 32 -but debugger: Microsoft Visual C++. ¡ Other: MASM 32. ¡

Two Types of Programs 16 -bit real-address mode: Run under MS-DOS and in the console window under MS-Windows. Written for the Intel 8086 and 8088 processors. Not discussed in this class. ¡ 32 -bit protected mode: All the programs in this class. ¡

Build Environments Microsoft Visual C++ installed. ¡ Install MASM 6. 15: ftp: //eec 751@ftp. csie. nuk. edu. tw ¡ Set tools: Build, run, and debug. http: //kipirvine. com/asm/4 th/ide/vs 6/index. htm ¡

A Simple C File ¡ #include <stdio. h> ¡ void main() { int i; ¡ ¡ i = 0 x 10000; i = i + 0 x 40000; i = i - 0 x 20000; printf("i= %dn", i); ¡ ¡ ¡ }

Into Assembly Language ¡ ¡ ¡ ¡ 3: void main() 4: { 0040 B 450 push ebp 0040 B 451 mov ebp, esp 0040 B 453 sub esp, 44 h 0040 B 456 push ebx 0040 B 457 push esi 0040 B 458 push edi 0040 B 459 lea edi, [ebp-44 h] 0040 B 45 C mov ecx, 11 h 0040 B 461 mov eax, 0 CCCCh 0040 B 466 rep stos dword ptr [edi] 5: int i; 6: 7: i = 0 x 10000; 0040 B 468 mov dword ptr [ebp-4], 10000 h

¡ ¡ ¡ ¡ 8: i = i + 0 x 40000; 0040 B 46 F mov eax, dword ptr [ebp-4] 0040 B 472 add eax, 40000 h 0040 B 477 mov dword ptr [ebp-4], eax 9: i = i - 0 x 20000; 0040 B 47 A mov ecx, dword ptr [ebp-4] 0040 B 47 D sub ecx, 20000 h 0040 B 483 mov dword ptr [ebp-4], ecx 10: printf("i= %dn", i); 0040 B 486 mov edx, dword ptr [ebp-4] 0040 B 489 push edx 0040 B 48 A push offset string "i= %dn" (0041 fe 50) 0040 B 48 F call printf (0040 b 710) 0040 B 494 add esp, 8 11: }

A Simple MASM File ¡ TITLE Add and Subtract ¡ ¡ ; This program adds and subtracts 32 -bit integers. ; Last update: 2/1/02 ¡ INCLUDE Irvine 32. inc ¡ . code main PROC ¡ ¡ ¡ ¡ mov eax, 10000 h add eax, 40000 h sub eax, 20000 h call Dump. Regs exit main ENDP END main (Add. Sub. asm) ; EAX = 10000 h ; EAX = 50000 h ; EAX = 30000 h

Portability Assembly language is not portable. ¡ Well-known processor families are Motorola 68 x 00, Intel IA-32, SUN Sparc, DEC Vax, and IBM-370. ¡

Applications Small embedded programs. ¡ Real-time applications. ¡ Computer game consoles. ¡ Help understand computer hardware and operating systems. ¡ Subroutines hand optimized for speed. ¡ Device drivers. ¡

Virtual Machines • Tanenbaum: Virtual machine concept • Programming Language analogy: • Each computer has a native machine language (language L 0) that runs directly on its hardware • A more human-friendly language is usually constructed above machine language, called Language L 1 • Programs written in L 1 can run two different ways: • Interpretation – L 0 program interprets and executes L 1 instructions one by one • Translation – L 1 program is completely translated into an L 0 program, which then runs on the computer hardware Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Translating Languages English: Display the sum of A times B plus C. C++: cout << (A * B + C); Assembly Language: Intel Machine Language: mov eax, A mul B add eax, C call Write. Int A 1 0000 F 7 25 00000004 03 05 00000008 E 8 00500000 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Specific Machine Levels (descriptions of individual levels follow. . . ) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Modes of Operation • Protected mode • native mode (Windows, Linux) • Real-address mode • native MS-DOS • System management mode • power management, system security, diagnostics • Virtual-8086 mode • hybrid of Protected • each program has its own 8086 computer Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Basic Execution Environment • • • Addressable memory General-purpose registers Index and base registers Specialized register uses Status flags Floating-point, MMX, XMM registers Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Addressable Memory • Protected mode • 4 GB • 32 -bit address • Real-address and Virtual-8086 modes • 1 MB space • 20 -bit address Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Microsoft Visual C++ Web site Examples

Flags Book OF Visual OV C D I x SF ZF x AC x P x CF UP EI x PL ZR x AC x PE x CY Web site Examples

General-Purpose Registers Named storage locations inside the CPU, optimized for speed. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Accessing Parts of Registers • Use 8 -bit name, 16 -bit name, or 32 -bit name • Applies to EAX, EBX, ECX, and EDX Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Index and Base Registers • Some registers have only a 16 -bit name for their lower half: Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Some Specialized Register Uses (1 of 2) • General-Purpose • • • EAX – accumulator ECX – loop counter ESP – stack pointer ESI, EDI – index registers EBP – extended frame pointer (stack) • Segment • • CS – code segment DS – data segment SS – stack segment ES, FS, GS - additional segments Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Some Specialized Register Uses (2 of 2) • EIP – instruction pointer • EFLAGS • status and control flags • each flag is a single binary bit Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Status Flags • Carry • unsigned arithmetic out of range • Overflow • signed arithmetic out of range • Sign • result is negative • Zero • result is zero • Auxiliary Carry • carry from bit 3 to bit 4 • Parity • sum of 1 bits is an even number Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Floating-Point, MMX, XMM Registers • Eight 80 -bit floating-point data registers • ST(0), ST(1), . . . , ST(7) • arranged in a stack • used for all floating-point arithmetic • Eight 64 -bit MMX registers • Eight 128 -bit XMM registers for singleinstruction multiple-data (SIMD) operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

IA-32 Memory Management • • • Real-address mode Calculating linear addresses Protected mode Multi-segment model Paging Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Real-Address mode • 1 MB RAM maximum addressable • Application programs can access any area of memory • Single tasking • Supported by MS-DOS operating system Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Segmented Memory linear addresses Segmented memory addressing: absolute (linear) address is a combination of a 16 -bit segment value added to a 16 -bit offset Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. one segment Web site Examples

Calculating Linear Addresses • Given a segment address, multiply it by 16 (add a hexadecimal zero), and add it to the offset • Example: convert 08 F 1: 0100 to a linear address Adjusted Segment value: 0 8 F 1 0 Add the offset: 0 1 0 0 Linear address: 0 9 0 1 0 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Protected Mode (1 of 2) • 4 GB addressable RAM • (0000 to FFFFh) • Each program assigned a memory partition which is protected from other programs • Designed for multitasking • Supported by Linux & MS-Windows Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Protected mode (2 of 2) • Segment descriptor tables • Program structure • code, data, and stack areas • CS, DS, SS segment descriptors • global descriptor table (GDT) • MASM Programs use the Microsoft flat memory model Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Flat Segment Model • Single global descriptor table (GDT). • All segments mapped to entire 32 -bit address space Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Multi-Segment Model • Each program has a local descriptor table (LDT) • holds descriptor for each segment used by the program Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Paging • Supported directly by the CPU • Divides each segment into 4096 -byte blocks called pages • Sum of all programs can be larger than physical memory • Part of running program is in memory, part is on disk • Virtual memory manager (VMM) – OS utility that manages the loading and unloading of pages • Page fault – issued by CPU when a page must be loaded from disk Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Levels of Input-Output • Level 3: Call a library function (C++, Java) • easy to do; abstracted from hardware; details hidden • slowest performance • Level 2: Call an operating system function • specific to one OS; device-independent • medium performance • Level 1: Call a BIOS (basic input-output system) function • may produce different results on different systems • knowledge of hardware required • usually good performance • Level 0: Communicate directly with the hardware • May not be allowed by some operating systems Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

Displaying a String of Characters When a HLL program displays a string of characters, the following steps take place: Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples

ASM Programming levels ASM programs can perform input-output at each of the following levels: Library Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Level 3 Web site Examples