Transcript ARMSim# and SWIInstructions Plug-in Group 11: Brian Knight Benjamin Moore Alex Williams Outline     Overview of SWIInstructions Plug-in for ArmSim# Basic SWI Operations for I/O Stdin/Stdout/Stderr View ArmSim# I/O Examples with.

ARMSim# and
SWIInstructions Plug-in
Group 11:
Brian Knight
Benjamin Moore
Alex Williams
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Outline
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Overview of SWIInstructions Plug-in for
ArmSim#
Basic SWI Operations for I/O
Stdin/Stdout/Stderr View
ArmSim# I/O Examples with SWI
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Printing Characters
Printing Strings
Determining Primes, Reading from Files and Printing to
Files
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SWIInstructions Plug-in Overview
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Implements Software Interrupt Codes to allow
for common I/O operations
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Included in ARMSim# 1.91 Download
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Enabled/Disabled via File->Preferences>Plugins->SWIInstructions
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Enabled by Default
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Types of I/O Operations
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Open/close files
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Write characters and strings to Stdout or file
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Reading from files and Stdin (Keyboard)
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Allocate/deallocate memory on Heap
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Interact with other Plug-ins (ex. Embest
Board)
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SWI Codes
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SWI Codes
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SWIcodes from 0 to 255 are forArmSim# I/O,
codes above 255 are used for interaction with
other ArmSim# plugin modules
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How SWI Works
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Not really an exception or a proper interrupt
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Enables the user to call routines in supervisor
mode
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Most ARM systems have a well-defined set of
operations accessible through SWI
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Outline




Overview of SWIInstructions Plug-in for
ArmSim#
Basic SWI Operations for I/O
Stdin/Stdout/Stderr View
ArmSim# I/O Examples with SWI



Printing Characters
Printing Strings
Determining Primes, Reading from Files and Printing to
Files
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Stdin/Stdout/Stderr View
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Where output from user programs is displayed
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Stdout: Output to file, pipe, or console
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Stderr: Output stream for errors
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Requests from Stdin freeze ARMSim# until
input is received
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Input is echoed in Stdin/Stdout/Stderr View
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Stdin/Stdout/Stderr View
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Example 1 – Printing Characters
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.equ [symbol], [swi code] makes
code more readable
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swi 0x00: Display character
stored in R0 to Stdout
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swi 0x11: Halt execution
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#’[char] uses ASCII value for
character like an immediate
value
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Example 2 – Printing Strings
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swi 0x02: Displays an ASCII
string to Stdout (Address in R0)
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String must be null-terminated
(.asciz)
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ASCII for “Hello World!\n” =
48,65,6C,6C,6F,20,57,6F,72,6C,
64,21,0A,00
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Little-endian byte address
assignment
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Outline




Overview of SWIInstructions Plug-in for
ArmSim#
Basic SWI Operations for I/O
Stdin/Stdout/Stderr View
ArmSim# I/O Examples with SWI



Printing Characters
Printing Strings
Determining Primes, Reading from Files and Printing
to Files
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Example 3 – Is Prime
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QUESTIONS?
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References
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http://armsim.cs.uvic.ca/index.html
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ARMSim_UserGuide4Plus.pdf
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ARM system-on-chip architecture, second edition,
Steve Furber, Addison Wesley, 2000
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BACK-UP SLIDES
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SWI Instructions step by step
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SVC mode is entered
R15 is saved to R14_SVC
The IRQ disable bit is set
The PC is set to address &00000008, this
address has the instruction which jumps to the
real SWI handler
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