This project has been created for my final year project in Computer Science at the University of York. My project is to write a binary translator from a register to a stack based processor architecture.
The intention for my project is to live translate the code as it is being executed, meaning that only the necessary code will be translated and therefore processing time will not be wasted by translating unused code. For example:
loadRegisters:
LOAD s0, FF ; Set register s0 to FF
LOAD s1, 1 ; Set register s1 to 1
JUMP callSubroutines ; Jump to callSubroutines label
setS2:
LOAD s2, EE ; Set register s2 to EE
RETURN ; Return to next value on program counter stack
setS3:
LOAD s3, DD ; Set register s3 to DD
RETURN ; Return to next value on program counter stack
callSubroutines:
ADD s0, s1 ; Store in s0 the value of s0 + s1 (FF + 01 = 00 and a carry bit)
CALL C, setS2 ; Call setS2 subroutine if the carry bit is set (it is here)
ADD s0, s1 ; Store in s0 the value of s0 + s1 (00 + 01 = 01 with no carry bit)
CALL C, setS3 ; Call setS3 subroutine if the carry bit is set (it isn't here)
LOAD s4, CC ; Set register s4 to CC
When this code is executed, the registers will become:
| s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7 | s8 | s9 | sA | sB | sC | sD | sE | sF |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 01 | 01 | EE | 00 | CC | 00 | 00 | 00 | 00 | 00 | 00 | 00 | 00 | 00 | 00 | 00 |
The loadRegisters, setS2 and callSubroutines sections will all be executed in their entirety, but the setS3
section will never be executed. Because of this, the most efficient translation of this code would translate
everything apart from the setS3 subroutine. An example of a translation of the above code to Jorvik-5 assembly is
as follows:
loadRegisters:
SSET FF ; (FF) Set top of stack to FF
STORE 0 ; (FF) Store FF in memory location 0
DROP ; () Drop value off stack
SSET 1 ; (1) Set top of stack to 1
STORE 1 ; (1) Store 1 in memory location 1
DROP ; () Drop value off stack
LBRANCH callSubroutines ; () Jump to line D
setS2:
SSET EE ; (EE) Set top of stack to EE
STORE 2 ; (EE) Store EE in memory location 2
DROP ; () Drop value off stack
RETURN ; () Return to next value on program counter stack
setS3: ; Not executed so not translated
callSubroutines:
FETCH 0 ; (FF) Set top of stack to value in memory location 0
FETCH 1 ; (FF, 1) Set top of stack to value in memory location 1
ADD ; (0) Add top two on stack
STORE 0 ; (0) Store result in memory location 0
DROP ; () Drop result from stack
CALLCARRY setS2 ; () Call subroutine setS2 if carry flag is set (it is)
FETCH 0 ; (0) Set top of stack to value in memory location 0
FETCH 1 ; (0, 1) Set top of stack to value in memory location 1
ADD ; (1) Add top two on stack
STORE 0 ; (0) Store result in memory location 0
DROP ; () Drop result from stack
CALLCARRY setS3 ; () Call subroutine setS3 if carry flag is set (it isn't)
SSET CC ; (CC) Set top of stack to CC
STORE 4 ; (CC) Store CC in memory location 0
DROP ; () Drop value from stack
This code uses the first 5 values in memory to simulate the registers s0 through s4.