A utility which adds function calling and return support to Hack ASM. I intend on implementing an assembler and emulator for the language as well.
Currently this preprocessor supports three instructions #call <label>, #ret, and #include. The #call instruction will store the current address and jump to the provided label. The #ret instruction will retrieve the stored address and jump back to it. It is capable of storing multiple addresses at once - the upper limit is 16382 deep or whenever you overwrite the stack. Input can be provided from stdin or as a filename as the first argument. The include directive will copy and process files onto the end of the file like the C++ #include directive. Files are added onto the end so as to not alter the program entrypoint.
#CALL TEST1
@END
(END)
0;JMP
(TEST1)
@5
D=A
@0
M=D
#RET
This is pretty much the minimal functioning use scenario. It will immediately jump to the function TEST1 - which will set @0 to 5 - and then it will jump back to right after #CALL TEST1. It produces the ASM below and may be invoked like so - hack-asm -p test_cases/function_test_easy
@16383
D=A-1
M=D
@0
// JUMPING TO LABEL TEST1
// STORE CURRENT ADDRESS
D=A
@16383
A=M
M=D
@16383
M=M-1
// STORED
@TEST1
0;JMP
@END
(END)
0;JMP
(TEST1)
@5
D=A
@0
M=D
// RETURN FROM STORED ADDRESS
@16383
M=M+1
@16383
A=M
A=M
D=A
@12
A=D+A
0;JMP
// RETURNED