Lecture 007

Array

Array Basics

Array Endianness: Endianness is only applicable to single variables, ie. only to each array element value, not to the order of elements in the array.

Notice val+1 is equivalent of &val[1], not bit addition
Example 1
Example 2

Nested Arrays

Multi-dimentional

Multidimentional
multi dimensional array does not align up memory within itself

Array-of-Array

Different in Assembly

Three Ways To Access Array

Fixed Array Assembly
Variable Array Assembly

Array Access Practice:

Array Access

Struct

Memory Location

Memory location of primitive are determined at compile time
The order of memory remains the same as declare order (even though other orderings can run faster)

Memory Alignment

Motivation

Memory accessed by (aligned) chunks of 4 or 8 bytes (system dependent)
Inefficient to load or store datum that spans cache lines (64 bytes). Intel states should avoid crossing 16 byte boundaries.
Virtual memory trickier when datum spans 2 pages (4 KB pages)

Note: to save space, order elements in struct by increasing or decreasing order

Floating Points

TODO: don't want to write this part

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