Add Pep8 Assembly language (#2070)

Pep/8 is a toy assembly language used in some universities for teaching
the basics of assembly and low-level programming.

Signed-off-by: Lucas Bajolet <lucas.bajolet@gmail.com>

samples/Pep8/stri_buf.pep

@@ -0,0 +1,61 @@
+main:
+
+; Reads a string in stdin, returns the buffer it was read in
+; Stops reading at the first encounter of a \n character.
+;
+; Parameters:
+;	void
+;
+; Returns:
+;	- X: Address of the buffer
+stri:		SUBSP	2, i
+		LDA	32, i
+		CALL	new
+		CPX	buflen, s
+		BRGE	strinlrg
+strinlrg:	LDA	buflen, d
+		LDX	2, i
+		CALL	mult
+		STA	buflen
+		CALL	new
+		
+buflen:		.EQUATE 0
+
+; Copies the content of a buffer to another one
+;
+; Parameters:
+;	- SP + 2: Destination buffer
+;	- SP + 4: Source buffer
+;	- SP + 6: Length to copy
+memcpy:		LDX	0, i
+memcplp:	CPX	cpylen, s
+		BREQ	memcpout
+		LDBYTEA	srcbuf, sxf
+		STBYTEA	dstbuf, sxf
+		ADDX	1, i
+		BR	memcplp
+memcpout:	RET0
+; Destination buffer
+dtsbuf:		.EQUATE 2
+; Source buffer
+srcbuf:		.EQUATE 4
+; Copy length
+cpylen:		.EQUATE 6
+
+; Allocates a new structure in the heap
+;
+; Parameters:
+;	- A: Length of the structure to allocate (bytes)
+;
+; Returns:
+;	- X: Address of the allocated structure
+new:		ADDA	hpptr, d
+		LDX	hpptr, d
+		STA	hpptr, d
+		RET0
+
+; Pointer to the next available byte on the heap
+hpptr:		.ADDRSS heap
+; Start of the heap
+heap:		.BLOCK 1
+	.END