Resistor Color

Instructions

If you want to build something using a Raspberry Pi, you'll probably use resistors. For this exercise, you need to know two things about them:

• Each resistor has a resistance value.
• Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.

To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values. Each band has a position and a numeric value.

The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.

In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands.

These colors are encoded as follows:

• black: 0
• brown: 1
• red: 2
• orange: 3
• yellow: 4
• green: 5
• blue: 6
• violet: 7
• grey: 8
• white: 9

The goal of this exercise is to create a way:

• to look up the numerical value associated with a particular color band
• to list the different band colors

Mnemonics map the colors to the numbers, that, when stored as an array, happen to map to their index in the array: Better Be Right Or Your Great Big Values Go Wrong.

More information on the color encoding of resistors can be found in the Electronic color code Wikipedia article.

Reserved Memory

The buffer for the input string uses bytes 64-191 of linear memory.

Arrays

WebAssembly does not have the concept of arrays. For the colors test, return a comma-delimited buffer of characters in the form: black,brown,red,orange,yellow,green,blue,violet,grey,white

You will then have to internally build an array of structures using offsets and lengths to provide structure around this buffer.

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Source

Maud de Vries, Erik Schierboom