Pixel Manipulation Language
Overview
This module specifies the syntax and semantics of an Assembly-like language limited to pixel manipulation on the display unit. The langauge will be a human-readable way of representing machine instructions for the display's chip.
Instructions
The language is ought to be simple and direct. Supported instructions are listed below illustrating how they should be written and a description of what each does is provided.
What you should know:
- The state of the pixel can be;
on->1off->0
- Manipulation of the pixels uses an abstract cursor consisting of two coordinates, x and y stored in internal registers of the chip.
| Instruction | Description |
|---|---|
NOOP | Performs no operations, useful for delays/timing |
RESET | Resets all pixels in the grid to 0 |
IRESET | Sets all pixels in the grid to 1 |
INVERT | Inverts all pixels in the grid switching every 1 to 0 and vice versa |
SET <0/1> | Switches the pixel at the cursor's position to either 1 or 0 |
MOVX <value> | Stores <value> as the x-coordinate of the cursor |
MOVY <value> | Stores <value> as the y-coordinate of the cursor |
ADDX <value> | Adds <value> to the cursor's x-coordinate |
ADDY <value> | Adds <value> to the cursor's y-coordinate |
SUBX <value> | Subtracts <value> from the cursor's x-coordinate |
SUBY <value> | Subtracts <value> from the cursor's y-coordinate |
According to the list above, there are two types of instructions;
SIMPLE: a simple instruction accept no argumentsVALUE: value instructions accept one and only one argument. The argument must be ofINTEGERtype.
For a full list of instructions, instruction format and available opcodes, check out the instruction set architecture.
Comments
In this language, comments are identified by lines(or a section of a line) starting with a semicolon ;.
Example:
; this is a comment
; another comment
RESET ; inline commentAliases
There exists several instructions whose functionality can be referenced by another name or at least easy to understand. Below is a list of aliases;
| Instruction | Aliases |
|---|---|
RESET | CLEAR, CLR |
Macros
Some features such as rendering a character, line or any graphic element requires a bit of sophisticated implementation. Therefore, these have been abstracted using built-in macros that is preprocessed before assembling: so the instruction is substituted by a series of small primitive instructions listed above. Think of them as already implemented, reusable functions that do the ~hard~ stuff built on top of supported instructions.
To distinguish builtin macros from instructions, the @ sign is prefix as an identifier of every macro statement.
| Macro | Description | |
|---|---|---|
| ✅ | @DRAWTEXT <x> <y> <text> | Renders the <text> string starting from position (<x>, <y>) |
| ✅ | @DRAWLINE <x1> <y1> <x2> <y2> | Draws a line from (<x0>, <y0>) to (<x1>, <y1>) using Bresenham's line algorithm |
| ✅ | @CLEARRECT <x> <y> <w> <h> | Draws a filled rectangle defined by the corners (<x>, <y>) and (<x>+<w>, <y>+<h>) |
| ✅ | @STROKERECT <x> <y> <w> <h> | Resets/clears the area in the rectangle defined by the corners (<x>, <y>) and (<x>+<w>, <y>+<h>) |
| ✅ | @FILLRECT <x> <y> <w> <h> | Draws a filled rectangle defined by the corners (<x>, <y>) and (<x>+<w>, <y>+<h>) |
| ✅ | @STROKEARC <x> <y> <r> <startAngle> <endAngle> | Draws an outlined arc centered at (<x>, <y>) with the given radius <r> from <startAngle> deg to <endAngle> deg |
| ⬜️ | @FILLARC <x> <y> <r> <startAngle> <endAngle> | Draws a filled arc centered at (<x>, <y>) with the given radius <r> from <startAngle> deg to <endAngle> deg |
Writing Programs
Writing programs is a breeze. In section, you'll find a recommend program structure and example programs.
For every new program, a brief comment with the title or name of the program should be appear on the first line followed by a blank line. It helps you or others(when you share) understand what the program is about. For example a simple hello world program would have
; program: hello worldA short description of the program is optional but also be added to give more details
; program: hello world
; desc: print 'HELLO WORLD!' on the screenFor the rest of the program, group instructions doing the same thing together followed by a blank line. For example: clear screen and then print hello world
; program: hello world
; clear screen
RESET
; print string from point (4,4)
@DRAWTEXT 4 4 'HELLO WORLD!'Live Demo
Implementation
View source on GitHub: source/lang/