自制简易编程语言 个人笔记（2）
https://github.com/lucyTheSlayer/orange
网上把tiny machine的源码下载下来，省的自己敲了，赶紧试了下自己生成的字节码，不出所料一大堆bug。
经过debug，总算是能跑个像样的程序了。
立马敲一个，就从最简单的计算阶乘开始：
#welcom to orange
#this program computes n! for the input n
#plz enjoy the fun
read n;
result := 1;
while(n>0){
result := result*n;
n := n-1 ;
#write n;
}
write result;与python一样，#为注释，用上篇的编译器编译之，得到如下字节码：
* TINY Compilation to TM Code
* File: hello.orangebc
* Standard prelude:
0: LD 6,0(0) load maxaddress from location 0
1: ST 0,0(0) clear location 0
* End of standard prelude.
2: IN 0,0,0 read integer value
3: ST 0,0(5) read: store value
* -> assign
* -> Const
4: LDC 0,1(0) load const
* <- Const
5: ST 0,1(5) assign: store value
* <- assign
* -> while
* -> Op
* -> Id
6: LD 0,0(5) load id value
* <- Id
7: ST 0,0(6) op: push left
* -> Const
8: LDC 0,0(0) load const
* <- Const
9: LD 1,0(6) op: load left
10: SUB 0,1,0 op >
11: JGT 0,2(7) br if true
12: LDC 0,0(0) false case
13: LDA 7,1(7) unconditional jmp
14: LDC 0,1(0) true case
* <- Op
* while: jump to end belongs here
* -> assign
* -> Op
* -> Id
16: LD 0,1(5) load id value
* <- Id
17: ST 0,0(6) op: push left
* -> Id
18: LD 0,0(5) load id value
* <- Id
19: LD 1,0(6) op: load left
20: MUL 0,1,0 op *
* <- Op
21: ST 0,1(5) assign: store value
* <- assign
* -> assign
* -> Op
* -> Id
22: LD 0,0(5) load id value
* <- Id
23: ST 0,0(6) op: push left
* -> Const
24: LDC 0,1(0) load const
* <- Const
25: LD 1,0(6) op: load left
26: SUB 0,1,0 op -
* <- Op
27: ST 0,0(5) assign: store value
* <- assign
28: LDA 7,-23(7) jmp back to loop
15: JEQ 0,13(7) while: jmp to end
* <- while
* -> Id
29: LD 0,1(5) load id value
* <- Id
30: OUT 0,0,0 write ac
* End of execution.
31: HALT 0,0,0
看上去相当的cooooooooooooooooooooooooooooool,用tiny machine执行之，
TM simulation (enter h for help)...
Enter command: g
Enter value for IN instruction: 5
OUT instruction prints: 120
HALT: 0,0,0
Halted
Enter command: c
Enter command: g
Enter value for IN instruction: 10
OUT instruction prints: 3628800
HALT: 0,0,0
Halted
Enter command:5！ = 120
10! = 3628800
完全okaaaaaaaaaaaaaaaay,真的coooooooooooooooooooool
一套编译执行的流程后，下一步的工作是自定义字节码，然后自己手撸一个vm，初步使其能够打印字符串。