Computer Science 237
Computer Organization

Lecture 14: More Subroutines in Assembly
Date: October 13, 2006

Announcements
- Computer Science colloquium today, 2:30 PM, TCL 206, Computer Science faculty discuss their research. Snacks upstairs before
- Free Google stuff in the CS office
- Lab next week: we will meet briefly in TCL 216 to set up your accounts to use LogicWorks and to learn the basics of that package
More Subroutines in Assembly
- Naming local variables - negative offsets from the frame pointer
- Dealing with pointers - always 32-bit entities (on the 68K) even when they point to a byte-sized or a word-sized entity
- Pointers are stored in address registers
- Access data through pointers using indirection
- By following pointers, we can modify variables on the stack in a different function's call frame
- Getting a pointer to a variable: LEA instruction
- Pushing a pointer to a variable right onto the stack: PEA instruction