;;
;; This macro also defines a label LABEL_entry.
initial_latest_entry = 0
-macro header label, name {
+macro header label, name, immediate {
local .string_end
label#_entry:
dq initial_latest_entry
+ if immediate eq
+ db 0
+ else
+ db 1
+ end if
db .string_end - ($ + 1)
db name
.string_end:
}
;; Define a Forth word that is implemented in assembly. See 'header' for details.
-macro forth_asm label, name {
- header label, name
+macro forth_asm label, name, immediate {
+ header label, name, immediate
dq .start
.start:
}
;; Define a Forth word that is implemented in Forth. (The body will be a list of
;; 'dq' statements.)
-macro forth label, name {
- header label, name
- dq docol
+macro forth label, name, immediate {
+ header label, name, immediate
+ dq DOCOL
}
-
-
segment readable executable
entry main
;; The codeword is the code that will be executed at the beginning of a forth
;; word. It needs to save the old RSI and update it to point to the next word to
;; execute.
-docol:
+header DOCOL, 'DOCOL'
pushr rsi ; Save old value of RSI on return stack; we will continue execution there after we are done executing this word
lea rsi, [rax + 8] ; RAX currently points to the address of the codeword, so we want to continue at RAX+8
next ; Execute word pointed to by RSI
;; This word is called at the end of a Forth definition. It just needs to
-;; restore the old value of RSI (saved by 'docol') and resume execution.
+;; restore the old value of RSI (saved by 'DOCOL') and resume execution.
forth_asm EXIT, 'EXIT'
popr rsi
next
;; entry.
forth_asm TCFA, '>CFA'
pop rax
- add rax, 8 ; [rax] = length of name
+ add rax, 8 + 1 ; [rax] = length of name
movzx rbx, byte [rax]
inc rax
add rax, rbx ; [rax] = codeword
;; Takes a string on the stack and replaces it with the decimal number that the
;; string represents.
forth_asm PARSE_NUMBER, 'PARSE-NUMBER'
- pop [parse_number.length] ; Length
- pop [parse_number.buffer] ; String pointer
+ pop rcx ; Length
+ pop rdi ; String pointer
push rsi
call parse_number
mov rdi, 0
syscall
-forth HELLO, 'HELLO'
- dq LIT, 'H', EMIT
- dq LIT, 'e', EMIT
- dq LIT, 'l', EMIT
- dq LIT, 'l', EMIT
- dq LIT, 'o', EMIT
- dq LIT, '!', EMIT
- dq NEWLINE
- dq EXIT
+;; Duplicate a pair of elements.
+forth_asm PAIRDUP, '2DUP'
+ pop rbx
+ pop rax
+ push rax
+ push rbx
+ push rax
+ push rbx
+ next
+
+;; Swap the top two elements on the stack.
+forth_asm SWAP, 'SWAP'
+ pop rax
+ pop rbx
+ push rax
+ push rbx
+ next
+
+;; Remove the top element from the stack.
+forth_asm DROP, 'DROP'
+ add rsp, 8
+ next
+
+forth_asm NOT_, 'NOT'
+ pop rax
+ cmp rax, 0
+ jz .false
+.true:
+ push 0
+ next
+.false:
+ push 1
+ next
;; The INTERPRET word reads and interprets user input. It's behavior depends on
-;; the current STATE. It provides special handling for integers. (TODO)
+;; the current STATE. It provides special handling for integers.
forth INTERPRET, 'INTERPRET'
+ ;; Read word
dq READ_WORD
- dq FIND
+ dq PAIRDUP
+ ;; Stack is (word length word length).
+ dq FIND ; Try to find word
+ dq DUP_
+ dq ZBRANCH, 8 * 22 ; Check if word is found
+
+ ;; - Word is found -
+
+ dq STATE, GET, ZBRANCH, 8 * 11 ; Check whether we are in compilation or immediate mode
+
+ ;; (Word found, compilation mode)
+ dq DUP_, IS_IMMEDIATE, NOT_, ZBRANCH, 8 * 6 ; If the word is immediate, continue as we would in immediate mode
+
+ ;; Otherwise, we want to compile this word
dq TCFA
+ dq COMMA
+ dq DROP, DROP
+ dq EXIT
+
+ ;; (Word found, immediate mode)
+ ;; Execute word
+ dq TCFA
+ ;; Stack is (word length addr)
+ dq SWAP, DROP
+ dq SWAP, DROP
+ ;; Stack is (addr)
dq EXEC
dq EXIT
+ ;; - No word is found, assume it is an integer literal -
+ ;; Stack is (word length addr)
+ dq DROP
+ dq PARSE_NUMBER
+
+ dq STATE, GET, ZBRANCH, 8 * 5 ; Check whether we are in compilation or immediate mode
+
+ ;; (Number, compilation mode)
+ dq LIT, LIT, COMMA
+ dq COMMA
+ dq EXIT
+
+ ;; (Number, immediate mode)
+ dq EXIT
+
;; .U prints the value on the stack as an unsigned integer in hexadecimal.
forth_asm DOTU, '.U'
mov [.length], 0
push rax
next
+forth_asm PUT_BYTE, 'C!'
+ pop rbx
+ pop rax ; Value
+ mov [rbx], al
+ next
+
+forth_asm GET_BYTE, 'C@'
+ pop rax
+ movzx rax, byte [rax]
+ push rax
+ next
+
+;; Add two integers on the stack.
+forth_asm PLUS, '+'
+ pop rax
+ pop rbx
+ add rax, rbx
+ push rax
+ next
+
+;; Calculate difference between two integers on the stack. The second number is
+;; subtracted from the first.
+forth_asm MINUS, '-'
+ pop rax
+ pop rbx
+ sub rbx, rax
+ push rbx
+ next
+
+;; Given two integers a and b on the stack, pushes the quotient and remainder of
+;; division of a by b.
+forth_asm TIMESMOD, '/MOD'
+ pop rbx ; b
+ pop rax ; a
+ mov rdx, 0
+ div rbx
+ push rax ; a / b
+ push rdx ; a % b
+ next
+
;; Get the location of the STATE variable. It can be set with '!' and read with
;; '@'.
forth STATE, 'STATE'
dq LIT, var_STATE
dq EXIT
+;; Get the location of the LATEST variable. It can be set with '!' and read with
+;; '@'.
+forth LATEST, 'LATEST'
+ dq LIT, latest_entry
+ dq EXIT
+
+;; Get the location at which compiled words are expected to be added. This
+;; pointer is usually modified automatically when calling ',', but we can also
+;; read it manually with 'HERE'.
+forth HERE, 'HERE'
+ dq LIT, here
+ dq EXIT
+
+forth COMMA, ','
+ dq HERE, GET, PUT ; Set the memory at the address pointed to by HERE
+ dq HERE, GET, LIT, 8, PLUS ; Calculate new address for HERE to point to
+ dq HERE, PUT ; Update HERE to point to the new address
+ dq EXIT
+
+;; Read user input until next " character is found. Push a string containing the
+;; input on the stack as (buffer length). Note that the buffer is only valid
+;; until the next call to S" and that no more than 255 character can be read.
+forth_asm READ_STRING, 'S"'
+ push rsi
+
+ mov [.length], 0
+
+.read_char:
+ mov rax, 0
+ mov rdi, 0
+ mov rsi, .char_buffer
+ mov rdx, 1
+ syscall
+
+ mov al, [.char_buffer]
+ cmp al, '"'
+ je .done
+
+ mov rdx, .buffer
+ add rdx, [.length]
+ mov [rdx], al
+ inc [.length]
+ jmp .read_char
+
+.done:
+ pop rsi
+
+ push .buffer
+ push [.length]
+
+ next
+
+;; CREATE inserts a new header in the dictionary, and updates LATEST so that it
+;; points to the header. To compile a word, the user can then call ',' to
+;; continue to append data after the header.
+;;
+;; It takes the name of the word as a string (address length) on the stack.
+forth_asm CREATE, 'CREATE'
+ pop rcx ; Word string length
+ pop rdx ; Word string pointer
+
+ mov rdi, [here] ; rdi = Address at which to insert this entry
+ mov rax, [latest_entry] ; rax = Address of the previous entry
+ mov [rdi], rax ; Insert link to previous entry
+ mov [latest_entry], rdi ; Update LATEST to point to this word
+
+ add rdi, 8
+ mov [rdi], byte 0 ; Insert immediate flag
+
+ add rdi, 1
+ mov [rdi], byte cl ; Insert length
+
+ ;; Insert word string
+ add rdi, 1
+
+ push rsi
+ mov rsi, rdx ; rsi = Word string pointer
+ rep movsb
+ pop rsi
+
+ ;; Update HERE
+ mov [here], rdi
+
+ next
+
+;; Mark the last added word as immediate.
+forth IMMEDIATE, 'IMMEDIATE', 1
+ dq LIT, 1
+ dq LATEST, GET
+ dq LIT, 8, PLUS
+ dq PUT_BYTE
+ dq EXIT
+
+;; Given the address of a word, return 0 if the given word is not immediate.
+forth IS_IMMEDIATE, 'IMMEDIATE?'
+ dq LIT, 8, PLUS
+ dq GET_BYTE
+ dq EXIT
+
+;; Enter immediate mode, immediately
+forth INTO_IMMEDIATE, '[', 1
+ dq LIT, 0, STATE, PUT_BYTE
+ dq EXIT
+
+;; Enter compilation mode
+forth OUTOF_IMMEDIATE, ']'
+ dq LIT, 1, STATE, PUT_BYTE
+ dq EXIT
+
+forth_asm TICK, "'"
+ lodsq
+ push rax
+ next
+
+forth_asm ROT, 'ROT'
+ pop rax
+ pop rbx
+ pop rdx
+ push rax
+ push rdx
+ push rbx
+ next
+
+forth_asm PICK, 'PICK'
+ pop rax
+ lea rax, [rsp + 8 * rax]
+ mov rax, [rax]
+ push rax
+ next
+
+forth_asm EQL, '='
+ pop rax
+ pop rbx
+ cmp rax, rbx
+ je .eq
+.noteq:
+ push 0
+ next
+.eq:
+ push 1
+ next
+
forth MAIN, 'MAIN'
- dq HELLO
dq INTERPRET
dq BRANCH, -8 * 2
dq TERMINATE
segment readable writable
+;; The LATEST variable holds a pointer to the word that was last added to the
+;; dictionary. This pointer is updated as new words are added, and its value is
+;; used by FIND to look up words.
latest_entry dq initial_latest_entry
;; The STATE variable is 0 when the interpreter is executing, and non-zero when
READ_WORD.rsi dq ?
READ_WORD.rbp dq ?
+READ_STRING.char_buffer db ?
+READ_STRING.buffer rb $FF
+READ_STRING.length dq ?
+
DOTU.chars db '0123456789ABCDEF'
DOTU.buffer rq 16 ; 64-bit number has no more than 16 digits in hex
DOTU.rbuffer rq 16
DOTU.length dq ?
DOTU.printed_length dq ?
+;; Reserve space for compiled words, accessed through HERE.
+here dq here_top
+here_top rq $4000
+
;; Return stack
rq $2000
return_stack_top:
projects / rrq / jonasforth.git / blobdiff