TinkerTwo scanner names from the price list.691 B of 691 B
Chapter 2 of 7
Point back
The price list repeats itself: both scanner rows spell out the same words. What if the second copy just pointed back at the first?
This chapter: How does pointing back at earlier bytes make a file smaller?
About this chapter
You will learn
- A pointer says: go back this far, copy this many
- Long repeats shrink most
- Unpacking copies the bytes back exactly
Words you’ll meet
- Pointer
- Go back this many bytes and copy this many: it stands in for a repeat.
- Literal
- A byte written out as it is, because no repeat covers it.
- LZ77
- Ziv and Lempel’s 1977 method: replace each repeat with a pointer to an earlier copy.
Step 1 of 4
replaces a repeat with a : go back this far, copy this many. The strip holds two scanner names.
Predict how many pointers.