What is wc64?

wc64 is a 64-bit implementation of Forth inspired by Tachyon, written for the FASM assembler.

The executable is currently at about 5000 bytes.

wc64 has a bunch of primitives and it:

• has a minimal "outer loop"
• can create colon-definitions,
• knows about immediate words,
• can make any syscall (with 0-6 arguments), and
• automatically loads a 'boot-file' named 'wc64-boot.fth' if it exists.

I am hoping I can do everything else in the high-level forth code.

Building wc64

• On Linux, use make. Requires that fasm is installed.

I actually directed Claude (Haiku 4.5 + Sonnet 4.5) to code most of it (with guidance from me), so I am hoping that it "understands" it well enough that it might be able to migrate it to another CPU/platform without too much trouble.

Built-in primitives:

Stack Manipulation

Word	Stack	Description
dup	(n -- n n)	Duplicate top of stack
drop	(n --)	Remove top of stack
swap	(n1 n2 -- n2 n1)	Swap top two stack items
over	(n1 n2 -- n1 n2 n1)	Copy second item to top

Arithmetic

Word	Stack	Description
+	(n1 n2 -- n3)	Add
-	(n1 n2 -- n3)	Subtract (n1 - n2)
*	(n1 n2 -- n3)	Multiply
/mod	(n1 n2 -- q r)	Quotient and remainder
1+	(n -- n')	Increment
1-	(n -- n')	Decrement
negate	(n -- -n)	Negate

Logical/Bitwise

Word	Stack	Description
and	(n1 n2 -- n3)	Bitwise AND
or	(n1 n2 -- n3)	Bitwise OR
xor	(n1 n2 -- n3)	Bitwise XOR
invert	(n -- ~n)	Bitwise NOT

Comparison

Word	Stack	Description
=	(n1 n2 -- f)	Equal (0 or -1)
<	(n1 n2 -- f)	Less than (0 or -1)
>	(n1 n2 -- f)	Greater than (0 or -1)

Memory Access

Word	Stack	Description
@	(addr -- n)	Fetch 64-bit cell from memory
!	(n addr --)	Store 64-bit cell to memory
c@	(addr -- c)	Fetch byte from memory
c!	(c addr --)	Store byte to memory

Return Stack

Word	Stack	Description
>r	(n --) (R: -- n)	Push to return stack
r@	(-- n) (R: n -- n )	Copy return stack top
r>	(-- n) (R: n --)	Pop from return stack

Literals & Code

Word	Stack	Description
lit	(-- n)	Push next cell as literal
lit,	(n --)	Compile n as literal
here	(-- addr)	Address of next code location
mem	(-- addr)	Base address of code memory
,	(n --)	Compile cell to HERE

I/O

Word	Stack	Description
emit	(c --)	Output character
type	(addr len --)	Output string
key	(-- c)	Read character from input
cr	(--)	Output newline

Dictionary

Word	Stack	Description
last	(-- addr)	Address of last dictionary entry
base	(-- addr)	Current number base
find	(cs -- addr)	Find word in dictionary (0 if not found)
add-word	(--)	Add the next word to dictionary

String Operations

Word	Stack	Description
s-len	(str -- n)	Length of null-terminated string
lcase	(c -- c')	Convert character to lowercase
s-eqi	(s1 s2 -- f)	Case-insensitive string equality
count	(cs -- str len)	Split counted string into address/length
next-word	(--)	Parse next word from input
>in	(-- addr)	Address of input position variable
wd	(-- addr)	Address of word buffer

Parsing

Word	Stack	Description
is-num	(cs -- n 1 | 0)	Parse number (decimal/hex/binary)

Control Flow

Word	Stack	Description
exit	(--)	Return from colon definition
branch	(--)	Unconditional branch
0branch	(f --)	Branch if zero

Locals (Temp Stack)

Word	Stack	Description
+L	(--)	Allocate locals frame (x, y, z)
-L	(--)	Free locals frame
x@	(-- x)	Fetch local variable x
x!	(n --)	Store to local variable x
x@+	(-- x)	Fetch x then increment
y@	(-- y)	Fetch local variable y
y!	(n --)	Store to local variable y
y@+	(-- y)	Fetch y then increment
z@	(-- z)	Fetch local variable z
z!	(n --)	Store to local variable z
z@+	(-- z)	Fetch z then increment

Code Compilation

Word	Stack	Description
immediate	(--)	Mark last-defined word as immediate

File I/O

Word	Stack	Description
fopen	(name flags -- fd)	Open file (Linux syscall)
fclose	(fd --)	Close file
fread	(buf len fd -- n)	Read from file
fwrite	(buf len fd -- n)	Write to file

System Calls

Word	Stack	Description
syscall0	(n -- r)	Make Linux syscall with 0 args
syscall1	(a1 n -- r)	Make Linux syscall with 1 arg
syscall2	(a1 a2 n -- r)	Make Linux syscall with 2 args
syscall3	(a1 a2 a3 n -- r)	Make Linux syscall with 3 args
syscall4	(a1 a2 a3 a4 n -- r)	Make Linux syscall with 4 args
syscall5	(a1 a2 a3 a4 a5 n -- r)	Make Linux syscall with 5 args
syscall6	(a1 a2 a3 a4 a5 a6 n -- r)	Make Linux syscall with 6 args

Other

Word	Stack	Description
outer	(str --)	Interpret string as Forth code
bye	(--)	Exit the system