;;
;; 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
+ dq 0
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, 16 ; [rax] = length of name
movzx rbx, byte [rax]
inc rax
add rax, rbx ; [rax] = codeword
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 rax, 0
+ mov [rdi], rax ; Set immediate flag
+
+ add rdi, 8
+ mov [rdi], rcx ; 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
+ dq EXIT
+
+;; Return 0 if the given word is not immediate.
+forth IS_IMMEDIATE, 'IMMEDIATE?'
+ dq FIND
+ dq LIT, 8, PLUS
+ dq GET
+ dq EXIT
+
forth MAIN, 'MAIN'
dq HELLO
dq INTERPRET
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
projects / rrq / jonasforth.git / blobdiff