Cirrus Logic CS485 Bedienungsanleitung PDF herunterladen (Seite 11)

CS485G Spring 2015 11

4. The microarchitecture describes how the architecture is implemented.

It includes the sizes of caches and the frequency at which the ma-

chine operates. It is not important for programming in assembler.

5. Components of importance to the assembler programmer

(a) Program counter (PC): a register containing the address of the

next instruction. Called EIP (x86) or RIP (x86 64)

(b) Registers, used for heavily-accessed data, with names speciﬁc

to the architecture. The set of all registers is sometimes called

the register ﬁle.

metic operation, such as “greater than zero”, useful for condi-

tional branch instructions.

(d) Memory, addressed by bytes, containing code (also called “text”

in Unix), data, and a stack (to support procedures).

15 Steps in converting C to object code

1. Say the code is in two ﬁles: p1.c and p2.c

2. To compile: gcc p1.c p2.c -o p, which puts the compiled pro-

gram in a ﬁle called p.

3. The gcc compiler ﬁrst creates assembler ﬁles (stored in /tmp, but

we can imagine they are called p1.s and p2.s).

4. It then runs the as assembler on those ﬁles, creating p1.o and p2.o.

5. It then runs the ld linker to combine those ﬁles with libraries (pri-

marily the C library libc) to create an executable ﬁle p. Libraries

provide code for malloc, printf, and others.

6. Some libraries are dynamically linked when the program starts to ex-

ecute, saving space in the executable ﬁle and allowing the operating

system to share code among processes.

7. Sample code:

1 int sum(int x, int y)

2 {

3 int t = x+y;

4 return t;

5 }

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Cirrus Logic CS485 Bedienungsanleitung Seite 11