CS2422 Assembly Language

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CS2422 Assembly Language System Programming

• November 21, 2006

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Todays Topics (1/2)

• Assignment 3
• Windows (graphics mode) programming.
• Linking to an assembly procedure.
• Setting up Visual C 2005 Express.

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References

• Setting up Platform SDK see the course webpage.
• Setting up Visual C 6.0 to compile and link
  assembly code with C or C code included in the
  download file
• theForgers Win32 API Tutorial http//winprog.org/
  tutorial. (Read at least the first two articles.)

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Demo

• The program creates a mosaic effect on your
  windows desktop.
• You need to set your display to use 24-bit or
  32-bit colors.
• Using ML.exe /Zi option to enable debugging
  directly within your assembly code at Visual C.
  (Already done for you if you use VC 2005
  Express.)

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Assembly Code to Be Written

• Mosaic(img, resX, resY,
• x, y, blockX, blockY)

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Example Code

• Mosaic_C_version() in main.c shows the algorithm.
• To run the assembly code, remember to comment
  out
• define MOSAIC_C_VERSION
• The Mosaic procedure in mosaic.asm gives an
  example of accessing parameters and local
  variables.

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Img a 2D Array

• The img is conceptually 2D, but stored as if it
  is a 1D array.
• A pixel at location (x, y) is stored at
• imgx y xRes
• Each pixel stores the Red, Green, Blue components
  of a color in 4 bytes
• struct
• BYTE rgbBlue
• BYTE rgbGreen
• BYTE rgbRed
• BYTE rgbReserved
• RGBQUAD

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Basic Structure of a Windows Program

• WinMain procedure.
• WinProc procedure.
• Section 11.2 explains the above in assembly. The
  C version in main.c might be easier to read.
• An excellent introductory material can be found
  at http//winprog.org/tutorial. (Read at least
  the first two articles.)

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WinMain Procedure

• Every Windows application needs a startup
  procedure, usually named WinMain, which is
  responsible for the following tasks

• Get a handle to the current program

• Load the programs icon and mouse cursor

• Register the programs main window class and
  identify the procedure that will process event
  messages for the window

• Create the main window

• Show and update the main window

• Begin a loop that receives and dispatches messages

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WinProc Procedure

• WinProc receives and processes all event messages
  relating to a window
• Some events are initiated by clicking and
  dragging the mouse, pressing keyboard keys, and
  so on
• WinProc decodes each message, carries out
  application-oriented tasks related to the message

WinProc PROC, hWndDWORD, handle to the
window localMsgDWORD, message
ID wParamDWORD, parameter 1
(varies) lParamDWORD parameter 2 (varies)
(Contents of wParam and lParam vary, depending on
the message.)
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What Will You Learn from This Assignment?

• Linking C and Assembly.
• The first step in Windows programming.
• Array processing.
• Implementation of nontrivial loops.

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Todays Topic (2/2)

• Chapter 1 of Becks System Software book.

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Study Guide

• 1.1 Introduction
• 1.2 System Software and Machine Architecture
• 1.3 The Simplified Instructional Computer (SIC)
• SIC Machine Architecture
• SIC/XE Machine Architecture
• SIC Programming Examples

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Introduction

• Definition of System software
• System software consists of a variety of programs
  that support the operation of a computer
• E.g. of system software
• Text editor, compiler, loader or linker,
  debugger, macro processors, operating system,
  database management systems, software engineering
  tools, .

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System Software and Machine Architecture (1/2)

• One characteristic in which most system software
  differs from application software is machine
  dependency
• System programs are intended to support the
  operation and use of the computer itself, rather
  than any particular application.

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System Software and Machine Architecture (2/2)

• Because most system software is
  machine-dependent, we must include real machines
  and real pieces of software in our study.
• Simplified Instructional Computer (SIC)
• SIC is a hypothetical computer that has been
  carefully designed to include the hardware
  features most often found on real machines, while
  avoiding unusual or irrelevant complexities

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The Simplified Instructional Computer (SIC)

• Like many other products, SIC comes in two
  versions
• The standard model
• An XE version
• extra equipments, extra expensive
• The two versions has been designed to be upward
  compatible

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SIC Machine Architecture (1/7)

• Memory
• Memory consists of 8-bit bytes
• Any 3 consecutive bytes form a word (24 bits)
• Total of 32768 (215) bytes in the computer memory

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SIC Machine Architecture (2/7)

• Registers
• Five registers
• Each register is 24 bits in length

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SIC Machine Architecture (3/7)

• Data Formats
• Integers are stored as 24-bit binary number
• 2s complement representation for negative values
• Characters are stored using 8-bit ASCII codes
• No floating-point hardware on the standard
  version of SIC

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SIC Machine Architecture (4/7)

• Instruction Formats
• Standard version of SIC

The flag bit x is used to indicate
indexed-addressing mode
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SIC Machine Architecture (5/7)

• Addressing Modes
• There are two addressing modes available
• Indicated by x bit in the instruction

(X) the contents of register X
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SIC Machine Architecture (6/7)

• Instruction Set
• Load and store registers
• LDA, LDX, STA, STX, etc.
• Integer arithmetic operations
• ADD, SUB, MUL, DIV
• All arithmetic operations involve register A and
  a word in memory, with the result being left in A
• COMP
• Conditional jump instructions
• JLT, JEQ, JGT
• Subroutine linkage
• JSUB, RSUB
• See appendix A, Page 495

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SIC Machine Architecture (7/7)

• Input and Output
• Input and output are performed by transferring 1
  byte at a time to or from the rightmost 8 bits of
  register A
• Test Device TD instruction
• Read Data (RD)
• Write Data (WD)

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SIC Programming Examples (Fig 1.2a)
LDA FIVE STA ALPHA LDCH CHARZ STCH C1 . . .
ALPHA RESW 1 one-word variable FIVE WORD 5 one-wo
rd constant CHARZ BYTE CZ one-byte
constant C1 RESB 1 one-byte variable
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SIC Programming Example (Fig 1.3a)
LDA ALPHA ADD INCR SUB ONE STA BETA LDA GAMM
A ADD INCR SUB ONE STA DELTA ... ... ONE WORD
1 one-word constant ALPHA RESW 1 one-word
variables BETA RESW 1 GAMMA RESW 1 DELTA RESW 1 IN
CR RESW 1
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SIC Programming Example (Fig 1.4a)
LDX ZERO initialize index register to
0 MOVECH LDCH STR1,X load char from STR1 to reg
A STCH STR2,X TIX ELEVEN add 1 to index,
compare to 11 JLT MOVECH loop if less
than . . . STR1 BYTE CTEST
STRING STR2 RESB 11 ZERO WORD 0 ELEVEN WORD 11
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SIC Programming Example (Fig 1.5a)
LDA ZERO initialize index value to
0 STA INDEX ADDLP LDX INDEX load index value to
reg X LDA ALPHA,X load word from ALPHA into reg
A ADD BETA,X STA GAMMA,X store the result in a
word in GAMMA LDA INDEX ADD THREE add 3 to
index value STA INDEX COMP K300 compare new
index value to 300 JLT ADDLP loop if less than
300 ... ... INDEX RESW 1 ALPHA RESW 100 array
variables100 words each BETA RESW 100 GAMMA RESW
100 ZERO WORD 0 one-word constants THREE WORD 3 K3
00 WORD 300
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SIC Programming Example (Fig 1.6)
INLOOP TD INDEV test input device JEQ INLOOP loop
until device is ready RD INDEV read one byte
into register A STCH DATA . . OUTLP TD OUTDEV t
est output device JEQ OUTLP loop until device is
ready LDCH DATA WD OUTDEV write one byte to
output device . . INDEV BYTE XF1 input device
number OUTDEV BYTE X05 output device
number DATA RESB 1
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SIC/XE Machine Architecture (1/13)

• Memory
• Maximum memory available on a SIC/XE system is 1
  megabyte (220 bytes)

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SIC/XE Machine Architecture (2/13)

• Registers
• Additional registers are provided by SIC/XE

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SIC/XE Machine Architecture (3/13)

• There is a 48-bit floating-point data type

F2(e-1024)
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SIC/XE Machine Architecture (4/13)

• Instruction Formats

Format 1 (1 byte)
Format 2 (2 bytes)
Format 3 (3 bytes)
Format 4 (4 bytes)
Formats 1 and 2 are instructions that do not
reference memory at all
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SIC/XE Machine Architecture (5/13)

• Addressing modes
• Base relative (n1, i1, b1, p0)
• Program-counter relative (n1, i1, b0, p1)
• Direct (n1, i1, b0, p0)
• Immediate (n0, i1, x0)
• Indirect (n1, i0, x0)
• Indexing (both n i 0 or 1, x1)
• Extended (e1)

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SIC/XE Machine Architecture (6/13)

• Base Relative Addressing Mode

n1, i1, b1, p0, TA(B)disp (0?disp
?4095)

• Program-Counter Relative Addressing Mode

n1, i1, b0, p1, TA(PC)disp (-2048?disp
?2047)
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SIC/XE Machine Architecture (7/13)

• Direct Addressing Mode

n1, i1, b0, p0, TAdisp (0?disp ?4095)
n1, i1, b0, p0, TA(X)disp (with index
addressing mode)
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SIC/XE Machine Architecture (8/13)

• Immediate Addressing Mode

n0, i1, x0, operanddisp

• Indirect Addressing Mode

n1, i0, x0, TA(disp)
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SIC/XE Machine Architecture (9/13)

• Simple Addressing Mode

i0, n0, TAbpedisp (SIC standard)
i1, n1, TAdisp (SIC/XE standard)
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SIC/XE Machine Architecture (10/13)

• Addressing Modes Summary (p.499)

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SIC/XE Machine Architecture (11/13)

• Instruction Format

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SIC/XE Machine Architecture (12/13)

• Instruction Set
• Instructions to load and store the new registers
• LDB, STB, etc.
• Floating-point arithmetic operations
• ADDF, SUBF, MULF, DIVF
• Register move instruction
• RMO
• Register-to-register arithmetic operations
• ADDR, SUBR, MULR, DIVR
• Supervisor call instruction
• SVC

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SIC/XE Machine Architecture (13/13)

• Input and Output
• There are I/O channels that can be used to
  perform input and output while the CPU is
  executing other instructions

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SIC/XE Programming Examples (Fig 1.2b)
SIC version
SIC/XE version
LDA 5 STA ALPHA LDCH 90 STCH C1 . . . ALP
HA RESW 1 C1 RESB 1
LDA FIVE STA ALPHA LDCH CHARZ STCH C1 . . .
ALPHA RESW 1 FIVE WORD 5 CHARZ BYTE CZ C1 RE
SB 1
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SIC/XE Programming Example (Fig 1.3b)
LDS INCR LDA ALPHA ADDR S,A SUB 1 STA BETA
LDA GAMMA ADDR S,A SUB 1 STA DELTA ... ...
ALPHA RESW 1 one-word variables BETA RESW 1 GAMMA
RESW 1 DELTA RESW 1 INCR RESW 1
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SIC/XE Programming Example (Fig 1.4b)
LDT 11 initialize register T to
11 LDX 0 initialize index register to
0 MOVECH LDCH STR1,X load char from STR1 to reg
A STCH STR2,X store char into STR2 TIXR T add 1
to index, compare to 11 JLT MOVECH loop if less
than 11 . . . STR1 BYTE CTEST
STRING STR2 RESB 11
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SIC/XE Programming Example (Fig 1.5b)
LDS 3 LDT 300 LDX 0 ADDLP LDA ALPHA,X
load from ALPHA to reg A ADD BETA,X STA GAMMA,X
store in a word in GAMMA ADDR S,X add 3 to
index value COMPR X,T compare to
300 JLT ADDLP loop if less than
300 ... ... ALPHA RESW 100 array variables100
words each BETA RESW 100 GAMMA RESW 100
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SIC/XE Programming Example (Fig 1.7b)