Lasagna

Note

This article is copied from the GitHub repository.

Basics

A program file, with extension .bin.lsg, is defined by a list of instructions (each being one byte), and corresponding arguments. If, at any point, the stack is popped without anything on it, the program will immediately halt with an error.

Text

A text representation of a program, with extension .txt.lsg, is formatted with one instruction per line.

Comments

Comments in textual form are any text surrounded by square brackets, with nesting allowed.

[This is a [comment]]

Load

There is a special case for load - you can load many bytes at once, and it's compiled to separate load instructions. There are 4 different ways to format this data: raw bytes, a string, an integer, or a float.

Bytes

Raw bytes are formatted with a pound sign, arbitrarily many bytes, and another pound sign.

# 01 23 45 67 89 AB CD EF # 01 23 45 67 89 AB CD EF

Float

Floats are stored in IEEE 754 format, using 32 bytes to store the value. All floats MUST be formatted with a number before and after the decimal point, and optionally with an exponent. Hexadecimal-style floats are not supported.

0.0, -6.2e1 00 00 00 00, C2 78 00 00

Integer

Integers are stored big-endian, two's complement, with 6 distinct types, marked with a suffix. Any integers that won't fit into their type will fail to compile to a binary program.

0_u8, -1_i8, 2_u16, -3_i16, 4_u32, -5_i32 00, FF, 00 02, FF FD, 00 00 00 04, FF FF FF FB

String

Strings are stored as ASCII, backwards in the stack, with a null byte at the end. They are stored backwards for ease of printing.

'Hello, world!' 00 21 64 6C 72 6F 77 20 2C 6F 6C 6C 65 48

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Instructions

Any invalid instruction will make the program fail before running. Each instruction is formatted as a kind, an index, and, 3 bits of a type (if applicable, else 000). In textual representation, the type of the operation, if applicable, is put after the instruction.

Type	Name	Bits
Unsigned 8-bit integer	u8	000
Signed 8-bit integer	i8	001
Unsigned 16-bit integer	u16	010
Signed 16-bit integer	i16	011
Unsigned 32-bit integer	u32	100
Signed 32-bit integer	i32	101
Float	float	110
String	str	111

Instruction	Typed?	Textual Representation	Description
00 000	No	noop	Does nothing.
00 001	Yes	load	Load the next value in the file to the stack.
00 010	Yes	take	Take a value from stdin and put it on the stack plus a true boolean byte, or if reading fails, just puts a false boolean byte.
00 011	Yes	put	Pop a value from the stack, and write to stdout. Failing to write still pops from the stack.
00 100	Yes	discard	Pop a value from the stack and discard it.
00 101	Yes	copy	Push the value on the stack to the stack again, copying it.
00 110	Yes	random	Push one random value to the stack. Invalid for strings and floats.
00 111	Yes	swap	Swap the last two values on the stack.
01 000	No	label	Defines a label that can be jumped to later. Followed by four bytes, being the label's ID. In textual representation, this is an arbitrarily long string, and each string is assigned an ID at compile time.
01 001	No	jump	Unconditionally jumps to the label in the next four bytes in the file. Like before, this is compiled from a string from textual representation, and it fails to compile if the label doesn't exist. If a label's byte ID does not exist, then this instruction is invalid. This pushes to a special jump stack.
01 010	No	jumpzero	Pops a byte from the stack, and if it is zero, jumps to the label in the next four bytes in the file. This pushes to a special jump stack.
01 011	No	jumpnonzero	Pops a byte from the stack, and if it is not zero, jumps to the label in the next four bytes. This pushes to a special jump stack.
01 100	No	return	Pops a from the jump stack (mentioned above), and jumps one past that jump instruction. If there is nothing left on the jump stack, then this immediately ends the program without error.
01 101	No	rotleft	Pops the last value from the stack and puts it at the start of the stack. This is equivalent to moving a "pop index offset" to the left, and this method of implementation may be faster.
01 110	No	rotright	Pops the first value from the stack and puts it at the end of the stack. This is equivalent to moving a "pop index offset" to the right, and this method of implementation may be faster.
01 111	No	fork	Spawns a new child of the process, and pushes a 00 if on the parent, and a 01 if on the child. The child process obtains a copy of the current stack and jump stack.
10 000	Yes	add	Pops two values of the specified type from the stack, adds them, and pushes the resulting value, plus a boolean byte indicating if overflow occurred. Invalid for strings. If you need concatenation, just push both strings and remove the null terminator.
10 001	Yes	subtract	Subtracts two values, and pushes the resulting value, plus a boolean byte indicating if overflow occurred. Invalid for strings.
10 010	Yes	multiply	Multiplies two values, and pushes the resulting value, plus a boolean byte indicating if overflow occurred. Invalid for strings.
10 011	Yes	divide	Divides two values, and pushes the resulting value, plus a boolean byte indicating if there was a divide by zero. Invalid for strings.
10 100	Yes	remainder	Gets the remainder after dividing two values, and pushes the resulting value, plus a boolean byte indicating if there was a divide by zero. Invalid for strings.
10 101	Yes	order	Pushes a 00 if the two given values are equal, a FF if the first is larger, a 01 if the second is larger, and a 7F if they cannot be compared.
10 110	Yes	shiftleft	Bit-shifts a value leftwards by another value, and pushes the resulting value, filling empty space with zeros and discarding bits outside. Invalid for strings and floats.
10 111	Yes	shiftright	Bit-shifts a value rightwards by another value, and pushes the resulting value, filling empty space with zeros and discarding bits outside. Invalid for strings and floats.
11	Yes x2	cast	Casts a value to another type, and if successful, pushes the result, then 01, to the stack. If the cast is invalid, pushes 00 to the stack.

Care must be taken to not confuse types of stack values.