memory structure

Μemory management at programming levels (high-> mid -> low (Assembly))

Table of contents

• Labs
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
• How to run
• Acknowledgments

Labs

1

Memory management and data structures

• Hexadeced representation.
• Ordering elements in memory using pointers and arrays.
• Structs declaration
  • 2 structs with different variable content
• Dynamic memory allocation
• Μemory use map

2

Structure management in memory using linked data list operations.

C

Menu for the options

• Create List
• Insert Element
  • (id, value)
• Delete First
• Print
  • Address/Value element
  • List count
  • List address
  • Address element field
  • List size (bytes)
  • Element size (bytes)

CLang

• Create List
• Insert Element
  • (id, value)
• Delete First
• Print element value
  
  
  
  
  

3

Deepening the understanding of memory function in Clang/understanding of Assembly

C

New operation

• Print function address
• Calculate list size to bytes from addresses that occupy items

CLang

Conversion of all the variables used in c Menu for the options using standards (reference registers, etc)

• Create List
• Insert Element
  • (id, value)
• Delete First
• Print
  • Address/Value element
  • List count
  • List address
  • Address element field
  • List size (bytes)
  • Element size (bytes)

Assembly

Menu options (no functionality)

4

Deepening the understanding of Clang/Assembly

CLang

Modification from previous implementation

• Create finite list
• Delete Last
• Print element with minimum value

Assembly

• 100 nodes on list (static array)
• Correctness of assembly contracts (register contracts)
• Menu functionality (#3)
• Jal commands for call functions
  
  
  
  
  

5

Modification from previous implementation

Assembly

• Ascending sort using recursive Merge sort ¹
  • Stack emerged
• Convert values from type int -> short

6

I/O Exceptions

Assembly

Management of input/output devices, using the memory display of the units I/O

Polling

Checking peripheral devices if they are ready to accept/export data without syscall (write_ch,read_ch).

Functions
write_ch	Reads register Transmission control (TC) / Check device (crosscheck instruction and LSB)
read_ch	Waiting for new registration
print_str	Candidate for printing char per char

Interrupts

Menu
Choice #1
Choice #2
Exit

Menu options for keyboard using interrupts * cflag, cdata for handler

Choice 1 for 1
Choice 2 for 2
Exit for space.
Message appears

How to run

C/CLang

1. Instal cygwin compiler for your operation system

https://www.cygwin.com/install.html

• Create folder Cygwin
• Open installer
• Install from internet
• Select your path folder
• Select + and install compiler and debugger
• Find gcc-core, gcc-g++, gdb, make
  
  

2. Configure PATH variable

• Go to System and Security in Control Panel
• Advanced System Settings
• Environmental Variables
• Add to path variable the path cygwin-directory\bin of your cygwin folder
  
  

3. Install Apache NetBeans (or any other C IDE)

https://netbeans.apache.org/download/index.html

4. Instal NetBeans plugins
5. Import .c files to your workspace or Create a new C project
6. Run your .c source files
7. To execute clang files, use gcc 5.2_ or below

Assembly

1. Install PCSpim from website

http://spimsimulator.sourceforge.net/

2. Install Notepad ² software (or mipster ³)
3. Simulator->Settings
   • Mapped I/O
   • Load Exception file
4. File->Reinitialize->Load File ⁴⁵ -> Run

For (#6), necessery modifications on file

• Exception file

lui $k1 0xFFFF
lw  $k0 4($k1)

la $t1, cdata
sw $k0,0($t1)
la $t1, cflag
addi $k0, $zero,1
sw $k0,0($t1)

Acknowledgments

Projects were created for the requirements of the lesson Digital Computers

Footnotes

1. https://en.wikipedia.org/wiki/Merge_sort#:~:text=In%20computer%20science%2C%20merge%20sort%20%28also%20commonly%20spelled,was%20invented%20by%20John%20von%20Neumann%20in%201945. ↩

2. MIPS simulator recognizes programs written in text editors ↩

3. https://mipster.software.informer.com/ ↩

4. Reinitialize and load every time you run the program ↩

5. Extension .asm to run files on SPIM ↩