working on bf.dsa (brainf##k interpreter) cos fun

resources/dsa/bf.dsa

@@ -0,0 +1,148 @@
+
+// a simple brainf##k interpreter, because I already wrote a compiler lol.
+
+include print "./lib/print.dsa"
+
+// "print hello world"
+db program: "++++++[>++++++++++++<-]>.>++++++++++[>++++++++++<-]>+.+++++++..+++.>++++[>+++++++++++<-]>.<+++[>----<-]>.<<<<<+++[>+++++<-]>.>>.+++.------.--------.>>+."
+db error: "Invalid Instruction!"
+dw stack: 0x10000
+dw input: 0x30000
+resb data: 1024
+
+// set up a stack so we can call functions
+_init_stack:
+    ldw stack, bpr
+    mov bpr, spr
+
+start:
+    // load the start of the program into rg0
+    lwi program, rg0
+
+    // rg0 is our instruction pointer
+    // rg1 is our data pointer
+    // acc is the value at the data pointer
+    // rg3 stores the current instruction
+    // rg4 is the expression nesting level.
+
+    lui rg8, 43 // + = 43 increment
+    lui rg9, 45 // - = 45 decrement
+    lui rga, 62 // > = 62 increment pointer
+    lui rgb, 60 // < = 60 decrement pointer
+    lui rgc, 46 // . = 46 output
+    lui rgd, 44 // , = 44 input
+    lui rge, 91 // [ = 91 loop start
+    lui rgf, 93 // ] = 93 loop end
+
+loop:
+    // load the current instruction into rg3
+    ldb rg0, rg3
+    inc rg0
+
+    // switch on the instruction
+    cmp rg3, rg8
+    jeq increment
+    cmp rg3, rg9
+    jeq decrement
+    cmp rg3, rga
+    jeq inc_ptr
+    cmp rg3, rgb
+    jeq dec_ptr
+    cmp rg3, rgc
+    jeq output
+    cmp rg3, rgd
+    jeq input
+    cmp rg3, rge
+    jeq expr_start
+    cmp rg3, rgf
+    jeq expr_end
+
+    // if we get here, we don't know what the instruction is
+    lwi error, rg0
+    push rg0
+    call print::print
+    pop zero
+    hlt
+
+// increment the current cell
+increment:
+    inc acc
+    jmp loop
+
+// decrement the current cell
+decrement:
+    dec acc
+    jmp loop
+
+// increment the pointer
+inc_ptr:
+    stw acc, rg1
+    addi rg1, 4
+    ldw rg1, acc
+    jmp loop
+
+// decrement the pointer
+dec_ptr:
+    stw rg1, acc
+    subi rg1, 4
+    ldw rg1, acc
+    jmp loop
+
+// print the byte in the current cell
+output:
+    push acc
+    call print::print_byte
+    pop zero
+    jmp loop
+
+// read a byte into the current cell
+input:
+    ldw input, acc
+    jmp loop
+
+expr_start:
+    cmp acc, zero
+    jeq _traverse_right
+    inc rg4
+    jmp loop
+
+expr_end:
+    cmp acc, zero
+    jne _traverse_left
+    dec rg4
+    jmp loop
+
+traverse_right_start:
+    // we need to traverse to the right until we find the closing bracket.
+    // for each open bracket, we push to the stack
+    // for each close bracket, we pop from the stack
+_traverse_right_loop:
+    inc rg0
+    ldb rg0, rg3
+
+    cmp rg3, rge
+    jeq _open
+
+    cmp rg3, rgf
+    jeq _close
+
+    jmp _traverse_right
+
+
+
+
+
+
+_open:
+    push rg4
+    inc rg4
+    jmp _traverse_right
+
+_close:
+    pop rg5
+    cmp rg4,
+    jmp _traverse_right
+
+
+
+_traverse_left: