GASM Reference

Instructions

[[path]]

`path { [i]begin[/i] | { [i]end[/i] | [i]close[/i] } | [span class="gasm-instruction"]to[/span] [i]x, y[/i]  }`
Marks paths.
Paths are closed shapes consisted of `line`s – even though they may not be drawn. Arguments (mutually exclusive):

• `begin`: begins a path. Does not draw anything, and is to be used by `fill`.
• `close` (or `end`): marks the end of the current path and automatically closes it with a `line`.
• `[span class="gasm-instruction"]to[/span]`: creates an invisible path in order to `fill` without borders (only a draft feature) (Unimplemented in JS-GASM) @unused

[[movp]]

`movp [i]x[/i], [i]y[/i] `
Marks the starting position of a `line` or `path`.

[[line]]

`line [i]x[/i], [i]y[/i] `
Marks the ending position of a line and draws it from the point set by `movp`.
The next line will start from the ending position of this line, if no `movp` or `path close` is called.

[[lwid]]

`lwid [i]number[/i] `
Sets the width of the line to be drawn by `line` in pixels.

[[fill]]

`fill `
@experimental
Fills the area marked/enclosed by `path`. If the path is not closed, it should automatically close it. (Experimental)

[[rgba]]

`rgba { line | fill }, { [i]#HEX_COLOR[/i] | [i]r, g, b[/i] }`
Sets the color used by instructions such as `line` and `fill`.
Its first parameter is the instruction. For the second parameter, a color value is to be specified; it could be any of the following:

• A hexadecimal value representing the rgba value, e.g. #aabbccdd, #ABC
• Four integers between 0 and 255 representing red, green and blue values,
  and an alpha between 0 and 1, e.g. `rgba 128, 64, 57, 0.5`

[[set]]

`set $.variable.name [value]`
All variables must have a namespace, i.e. the default namespace `$.` in order to distinguish them from the registers.

[[del]]

`del $.variable.name`
@experimental
Removes a variable. It could not be referenced from now on.

[[print]]

`print { text | number | $variable, ...}`
Prints a message onto the standard output, e.g. the browser's Javascript developer console, or the GASM Console.

[[func]]

`func [b]function_name[/b] [i]arguments...[/i]`
Defines a function.

• function_name - The name of the function
  • The name may contain namespace(s): e.g. `func .util.main.draw_image` @draft @experimental
• arguments... - The arguments @draft @unsupported

[[call]]

`call func_name [ [i]arg1, arg2...[/i] ]`
Calls a function. The function could either be a custom function, or a predefined standard function – refer to the JS-GASM implementations below:

[[ret]]

`ret [value]`
@experimental
Returns a value from the current function.
Sets the register `$ret` to the value and exits.

[[dump]]

@experimental
Will dump the values of every register in the standard output for debugging purposes.

Common Operations

Common operations include the following (shown through the JS-GASM implementation again): Adding an `s` (for "self") after the operation will cause GASM to store the result in the variable given in the first parameter, e.g. `adds $.a, 3 ; add 3 to $.a`.

Common Conditionals

Conditional instructions, called "conditionals" in GASM, will only be executed if the condition set for the result of the last `cmp` instruction is true.
It includes the following: `e, ne, g, ge, l, le`.
`e` means equal, and `g` and `l` mean greater or lesser.
They are to be combined with `call` or `set`, like `sle` or `cg`, e.g. ```add 1, 1 cmp $add, 2 cge printn 1, 2, 3 ; only calls printn(1, 2, 3) if 1 + 1 >= 2 ```