<===========================>
<===== Project AuR_ASM =====>
<===========================>
| 16bit Architecture for a Virtual CPU Simulator
| using the .Net v4.7 framework.
|
| Features include simple keyboard input and simple output
| to a virtual screen.
| Intended use is for educational purposes to explore,
| learn, and understand: assembly language, assemblers,
| machine code, how CPUs work, and why explorer.exe keeps crashing.


<====================>
<===== Notation =====>
<====================>
| <reg> - Any register (r0 - r11)
| <val> - Any 32bit constant value
| <mem> - Any 32bit memory address

<=====================>
<===== Registers =====>
<=====================>
| Registers use 4bit addressing

=== Register Addresses: (16 Registers) ===
0	r0
1	r1
2	r2
3	r3
4	r4
5	r5
6	r6
7	r7
8	r8
9	r9
10	r10
11	r11
12	Base Pointer (BP)
13	Stack Pointer (SP)
14	Control Register (CR)
15	Instruction Pointer (IP)

=== Control Register Flag Bits ===
0	Carry Flag (CF)
1	Zero Flag (ZF)
2	Test Flag (TF)
3	Sign Flag (SF)
4	Interrupt Flag (IF)
5
6
7
8
9
10
11
12
13
14
15


<===========================>
<===== Instruction Codes ===>
<===========================>
| Using any instruction that doesn't have a function
|  will result in the program terminating
| Instruction set uses 8bit addressing

=== MISC ===

0	-	HALT
1	-
2	-
3	-
4	-
5	-
6	-
7	-
8	-
9	-
10	-
11	-
12	-
13	-
14	-
15	-
16	-	SYS <reg>
17	-	SYS <val>
18	-
19	-
20	-
21	-
22	-
23	-
24	-
25	-
26	-
27	-
28	-
29	-
30	-
31	-

=== Logic ===
| Modifies ZF
| Returns result to left operand

32	-	AND <reg>, <reg>
33	-	AND <reg>, <val>

34	-	OR <reg>, <reg>
35	-	OR <reg>, <val>

36	-	XOR <reg>, <reg>
37	-	XOR <reg>, <val>

38	-	NOT <reg>

=== Arithmetic ===
| Modifies CF and ZF
| Returns result to left operand

40	-	ADD <reg>, <reg>
41	-	SUB <reg>, <reg>
42	-	MUL <reg>, <reg>
43	-	DIV	<reg>, <reg> (left = Quotient, right = Remainder)

=== Memory ===

48	-	MOV <reg>, <reg>
49	-	MOV <reg>, <val>

50	-	INC <reg>
51	-	DEC <reg>

52	-	SHL <reg>
53	-	SHL	<reg>, <reg> (Result goes into left operand)
54	-	SHL <reg>, <val> (Result goes into left operand)

55	-	SHR <reg>
56	-	SHR	<reg>, <reg> (Result goes into left operand)
57	-	SHR <reg>, <val> (Result goes into left operand)

64	-	R8 <reg>, <mem>
65	-	R16 <reg>, <mem>
66	-	R32 <reg>, <mem>

67	-	W8 <reg>, <mem>
68	-	W16 <reg>, <mem>
69	-	W32 <reg>, <mem>

70	-	PUSH <reg>
71	-	POP <reg>

=== Compare ===
| Modifies TF

80 -	TEST <reg> = <reg>
81 -	TEST <reg> = <val>

82 -	TEST <reg> < <reg>
83 -	TEST <reg> < <val>

84 -	TEST <reg> > <reg>
85 -	TEST <reg> > <val>

86 -	TEST <reg> <= <reg>
87 -	TEST <reg> <= <val>

88 -	TEST <reg> >= <reg>
89 -	TEST <reg> >= <val>

=== Jump ===
| Checks TF

100	-	JMP <reg>
101	-	JMP <mem>
102	-	JMP <val>

103	-	JT <reg>
104	-	JT <mem>
105	-	JT <val>

106	-	JF <reg>
107	-	JF <mem>
108	-	JF <val>

=== Call ===
| Pushes current position + 1 onto the call stack before
| jumping to specified address

128	-	RET

129	-	CALL <reg>
130	-	CALL <mem>
131	-	CALL <val>


<========================>
<===== System Calls =====>
<========================>
|

Hex	| --------- Name -------------- | - Registers ----------------------------- +
---	| ----------------------------- | -- r0 -- | -- r1 -- | -- r2 -- | -- r3 -- |
 __	|  0	-	                    |          |          |          |          | (Nothing)
 __	| 10	-	Enable/Disable Scrn |     Bool |          |          |          | (Turns the screen on/off)
 __	| 11	-	Clear Screen        |          |          |          |          | (Resets the screen to blank state)
 __	| 12	-	Read input          |  KeyCode |          |          |          | (Reads a byte from the input buffer)
 __	| 32	-	Set Pixel           |        X |        Y |  ColorID |          | (Sets pixel at X,Y to whatever the color code value is in r2)
 __	| 33	-	Get Pixel Color     |        X |        Y |  ColorID |          | (Returns pixel color at X,Y to r2)
 __	| 36	-	SetPrint Char       |        X |        Y |  PrintID |          | (Blockland Only)
 __	| 37	-	GetPrint Char       |        X |        Y |  PrintID |          | (Blockland Only)