bf.asm

ASCII EQUS " 
\t\n\r !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz\{|}~"

bf: MACRO
; Run a brainfuck program.
; bf source[, input]

; point to the first program char
src_i = 1
src_len = STRLEN("\1")

; point to the first input char
in_p = 1
in_len = 0
if _NARG > 1
in_len = STRLEN("\2")
endc

; point to the first cell
mem_p = 0
mem_len = 32768
cell_size = 256
; initialize 32768 memory cells to 0s
for i, mem_len
mem{d:i} = 0
endr

; run the program
rept $7fffffff
if src_i > src_len
	break
endc

; get the current source code character
x = STRSUB("\1", src_i, 1)

; increment the current cell
if x == "+"
mem{d:mem_p} = (mem{d:mem_p} + 1) % cell_size

; decrement the current cell
elif x == "-"
mem{d:mem_p} = (mem{d:mem_p} - 1) % cell_size

; move to the next cell
elif x == ">"
mem_p = (mem_p + 1) % mem_len

; move to the previous cell
elif x == "<"
mem_p = (mem_p - 1) % mem_len

; output the current cell
elif x == "."
print STRSUB("{ASCII}", mem{d:mem_p} + 1, 1)

; input the current cell
elif x == ","
if in_p <= in_len
mem{d:mem_p} = STRSUB("\2", in_p, 1)
in_p = in_p + 1
else
mem{d:mem_p} = cell_size - 1 ; EOF
endc

; begin while loop
elif x == "["
if mem{d:mem_p} == 0
if !DEF(pair{d:src_i})
; find the corresponding ']' after the '['
depth = 1
for i, src_i + 1, src_len + 1
y = STRSUB("\1", i, 1)
depth = depth + (y == "[") - (y == "]")
if depth == 0
	break
endc
endr
if i == src_len
	fail "[ without ]"
endc
pair{d:src_i} = i
endc
src_i = pair{d:src_i}
endc

; end while loop
elif x == "]"
if mem{d:mem_p} != 0
if !DEF(pair{d:src_i})
; find the corresponding '[' before the ']'
depth = 1
for i, src_i - 1, 0, -1
y = STRSUB("\1", i, 1)
depth = depth - (y == "[") + (y == "]")
if depth == 0
	break
endc
endr
if i == 0
	fail "] without ["
endc
pair{d:src_i} = i
endc
src_i = pair{d:src_i}
endc

endc

; move to the next source code character
src_i = src_i + 1

endr

ENDM

; hello world
	bf ++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.
; echo
	bf \,+[-.\,+], HELLO WORLD!\n