Cirrus Logic CS485 Manual de usuario descargar pdf (Pagina 8)

CS485G Spring 2015 8

6. A buffer is also an array of bytes, typically used to hold data sub-

ject to I/O. The bytes hold arbitrary binary values, not necessarily

printable values.

7. Declaration

(a) char

myBuffer;

(b) char myBuffer[];

8. Buffers are not null-terminated; you need a separate variable to re-

member how much data is in the buffer.

10 Boolean algebra

1. Lecture 6, 1/28/2015

2. Named after George Boole (1815–1864).

3. A computer’s circuitry uses pieces that accomplish Boolean func-

tions in order to build both combinatorial and sequential circuits.

4. We are familiar with the truth tables for and (in C: &), or (|), not (˜).

We might not be familiar with exclusive or (xor, ˆ).

5. When one operates on bytes (or larger chunks such as integers) with

Boolean functions, they are applied bitwise. Examples:

01101001 105

&01010101 85

========

01000001 65

6. Instead of interpreting 32 bits as an integer, we can interpret it as a

subset of {0, . . . , 31}. Each 1 bit represents a number in that range

that is in the set; every 0 bit represents a number that is not in the set.

So 1001 represents the set 0, 3. Then:

(a) & is intersection.

(b) | is union.

(d) ˜ is complement.

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Cirrus Logic CS485 Manual de usuario Pagina 8