UMBC CMSC 313, Computer Organization & Assembly Language, Fall 2002, Section 0101

The Stack & C Functions II

Thursday 10/10, 2002

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Assigned Reading in Murdocca & Heuring:  7.7

Assigned Reading in Neveln:  8.1-8.8

Assigned:  Proj4

Due:  Proj3

Topics Covered:

• We continued discussion of C function call conventions.
• We looked examples of calling C functions from assembly language programs (e.g., calling printf()). We used gcc to link/load the program to avoid having to figure out the options to give to ld to get this to work.
• We looked at C programs calling assembly language functions.

Programs shown:

• A more complicated C function converted to assembly language using gcc -S (shown only briefly): cfunc.c, cfunc2.s (AT&T style assembly), cfunc2.asm (Intel style assembly).
• A C function with a return value with size more than 4 bytes (shown only briefly): cfunc3.c, cfunc3.asm (The comments in this file were added afterwards).
• An assembly language program that calls printf to write to stdout (with C style main function): printf1.asm, printf1.txt.
• An assembly language program that calls printf to write to stdout (with assembly style _start entry point): printf2.asm, printf2.txt.
• An example of a C program that calls a function implemented in assembly: arraytest.c, arrayinc.asm, arraytest.txt.