{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

1-Program-Structure

1-Program-Structure - PROGRAM STRUCTURE CS252 SYSTEMS...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
PROGRAM STRUCTURE CS252: SYSTEMS PROGRAMMING Charles Killian Computer Science Department Purdue University With slide credits to Gustavo Rodriguez-Rivera and others.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Memory of a Program A program sees memory as an array of bytes that goes from address 0 to 2 32 -1 (0 to 4GB-1) [32-bit architecture] A program sees memory as an array of bytes that goes from address 0 to 2 64 -1 (0 to 16EiB-1) [64-bit architecture] 0 (16EiB-1) 2 64 -1
Image of page 2
Memory Sections The memory is organized into sections called memory mappings . Stack Text Data Bss Heap Shared Libs 0 2 64 -1
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Memory Sections Each section has different permissions: read/write/ execute or a combination of them. Text – Instructions that the program runs Data – Initialized global variables. Bss – Uninitialized global variables. They are initialized to zeroes. Heap – Memory returned when calling malloc/new. It grows upwards. Stack – It stores local variables and return addresses. It grows downwards.
Image of page 4
Memory Sections Dynamic libraries – They are libraries shared with other processes. Each dynamic library has its own text, data, and bss. Each program has its own view of the memory that is independent of each other. This view is called the Address Space of the program. If a process modifies a byte in its own address space, it will not modify the address space of another process.
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Example Program hello.c int a = 5; // Stored in data section int b[20]; // Stored in bss int main() { // Stored in text int x; // Stored in stack int *p =(int*) malloc(sizeof(int)); //In heap }
Image of page 6
Memory Gaps Between each memory section there may be gaps that do not have any memory mapping.
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern