# Trigonometric functions table generator (assembler NASM)

<img scr="trigonometric-table.png" />

## Introduction

The table generator that contains values of trigonometric functions for given
angles. This program saves the result to a file.

Trigonometric functions:

- sine
- cosine
- tangent
- cotangent

## Implementation (TL;DR)

Floating point arithmetic is implemented via an arithmetic coprocessor.

It is a kind of stack of its own registers R0, R1, ..., R7. Each of the
registers can be the top of the stack (indicated by ST0).

The coprocessor uses its own commands for data exchange (e.g., load to the top
of the stack, also called register, fild), state flag registers (CR, SR, TW),
commands for arithmetic operations (fsin, fcos, fptan).

Fptan calculates a value in a very interesting way: it places 1 on the top of
the stack (ST0), and places the result (the tangent value) behind the top (ST1).

That is done to simplify the calculation of cotangent ($`1/tang`$).

Therefore, we divide ST0 by ST1 using the fdivp command, and the result is
written to the top of the stack.

## Building


```
git clone https://git.scratko.xyz/trigonometric-table
cd trigonometric-table
make
```

## Usage

After executing above commands:

```
./trigonometric-table <1st> <2nd> <3rd> <4th>
```

Where:

- <1st> name of a file
- <2nd> initial angle
- <3rd> final angle
- <4th> distance step

In the same directory there will be the file with the result.