From be8f6fc600856043dede3a5da6aa9aded19fcb34 Mon Sep 17 00:00:00 2001 From: Jonas Hvid Date: Mon, 25 Nov 2019 20:26:48 +0100 Subject: [PATCH] Add metadata to all words using macro --- main.asm | 155 ++++++++++++++++++++----------------------------------- 1 file changed, 55 insertions(+), 100 deletions(-) diff --git a/main.asm b/main.asm index 3da2e87..834872c 100644 --- a/main.asm +++ b/main.asm @@ -23,6 +23,42 @@ macro popr x { add rbp, 8 } +;; The following macro generates the dictionary header. It updates the +;; initial_latest_entry variable, which is used as the initial value of the +;; latest_entry variable that is made available at runtime. +;; +;; The header contains a link to the previous entry, the length of the name of +;; the word and the word itself as a string literal. +;; +;; This macro also defines a label LABEL_entry. +initial_latest_entry = 0 +macro header label, name { + local .string_end + +label#_entry: + dq initial_latest_entry + db .string_end - ($ + 1) + db name + .string_end: +label: + +initial_latest_entry = label#_entry +} + +;; Define a Forth word that is implemented in assembly. See 'header' for details. +macro forth_asm label, name { + header label, name + 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 +} + segment readable executable main: @@ -44,38 +80,20 @@ docol: ;; 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. -EXIT_entry: - dq 0 - db 4 - db 'EXIT' -EXIT: - dq .start -.start: +forth_asm EXIT, 'EXIT' popr rsi next ;; LIT is a special word that reads the next "word pointer" and causes it to be ;; placed on the stack rather than executed. -LIT_entry: - dq EXIT_entry - db 3 - db 'LIT' -LIT: - dq .start -.start: +forth_asm LIT, 'LIT' lodsq push rax next ;; Given a string (a pointer following by a size), return the location of the ;; dictionary entry for that word. If no such word exists, return 0. -FIND_entry: - dq LIT_entry - db 4 - db 'FIND' -FIND: - dq .start -.start: +forth_asm FIND, 'FIND' mov [.rsi], rsi pop [.search_length] pop [.search_buffer] @@ -115,20 +133,12 @@ FIND: ;; BRANCH is the fundamental mechanism for branching. BRANCH reads the next word ;; as a signed integer literal and jumps by that offset. -BRANCH_entry: - dq FIND_entry - db 6 - db 'BRANCH' -BRANCH: - dq .start -.start: +forth_asm BRANCH, 'BRANCH' add rsi, [rsi] ; [RSI], which is the next word, contains the offset; we add this to the instruction pointer. next ; Then, we can just continue execution as normal ;; 0BRANCH is like BRANCH, but it jumps only if the top of the stack is zero. -ZBRANCH: - dq .start -.start: +forth_asm ZBRANCH, '0BRANCH' ;; Compare top of stack to see if we should branch pop rax cmp rax, 0 @@ -140,9 +150,7 @@ ZBRANCH: next ;; Expects a character on the stack and prints it to standard output. -EMIT: - dq .start -.start: +forth_asm EMIT, 'EMIT' pushr rsi pushr rax mov rax, 1 @@ -156,28 +164,20 @@ EMIT: next ;; Prints a newline to standard output. -NEWLINE: - dq docol +forth NEWLINE, 'NEWLINE' dq LIT, $A dq EMIT dq EXIT ;; Prints a space to standard output. -SPACE_entry: - dq BRANCH_entry - db 5 - db 'SPACE' -SPACE: - dq docol +forth SPACE, 'SPACE' dq LIT, ' ' dq EMIT dq EXIT ;; Read a word from standard input and push it onto the stack as a pointer and a ;; size. The pointer is valid until the next call to READ_WORD. -READ_WORD: - dq .start -.start: +forth_asm READ_WORD, 'READ-WORD' mov [.rsi], rsi mov [.rax], rax @@ -229,9 +229,7 @@ READ_WORD: ;; Takes a string on the stack and replaces it with the decimal number that the ;; string represents. -PARSE_NUMBER: - dq .start -.start: +forth_asm PARSE_NUMBER, 'PARSE-NUMBER' pop [.length] ; Length pop rdi ; String pointer mov r8, 0 ; Result @@ -275,17 +273,14 @@ PARSE_NUMBER: next -READ_NUMBER: - dq docol +forth READ_NUMBER, 'READ-NUMBER' dq READ_WORD dq PARSE_NUMBER dq EXIT ;; Takes a string (in the form of a pointer and a length on the stack) and ;; prints it to standard output. -TELL: - dq .start -.start: +forth_asm TELL, 'TELL' mov rbx, rsi mov rcx, rax @@ -300,36 +295,12 @@ TELL: next ;; Exit the program cleanly. -TERMINATE: - dq .start -.start: +forth_asm TERMINATE, 'TERMINATE' mov rax, $3C mov rdi, 0 syscall -PUSH_HELLO_CHARS: - dq docol - dq LIT, $A - dq LIT, 'o' - dq LIT, 'l' - dq LIT, 'l' - dq LIT, 'e' - dq LIT, 'H' - dq EXIT - -PUSH_YOU_TYPED: - dq .start -.start: - push you_typed_string - push you_typed_string.length - next - -HELLO_entry: - dq SPACE_entry - db 5 - db 'HELLO' -HELLO: - dq docol +forth HELLO, 'HELLO' dq LIT, 'H', EMIT dq LIT, 'e', EMIT dq LIT, 'l', EMIT @@ -340,13 +311,7 @@ HELLO: dq EXIT ;; .U prints the value on the stack as an unsigned integer in hexadecimal. -DOTU_entry: - dq HELLO_entry - db 2 - db '.U' -DOTU: - dq .start -.start: +forth_asm DOTU, '.U' mov [.length], 0 mov [.printed_length], 1 pop rax ; RAX = value to print @@ -406,25 +371,15 @@ DOTU: pop rsi next -MAIN: - dq docol +forth MAIN, 'MAIN' dq HELLO - dq LIT, SPACE_entry, DOTU, NEWLINE - dq LIT, HELLO_entry, DOTU, NEWLINE - dq LIT, DOTU_entry, DOTU, NEWLINE - dq LIT, SPACE_string, LIT, SPACE_string.length, TELL, SPACE - dq LIT, SPACE_string, LIT, SPACE_string.length, FIND, DOTU, NEWLINE - dq LIT, HELLO_string, LIT, HELLO_string.length, TELL, SPACE - dq LIT, HELLO_string, LIT, HELLO_string.length, FIND, DOTU, NEWLINE - dq LIT, DOTU_string, LIT, DOTU_string.length, TELL, SPACE - dq LIT, DOTU_string, LIT, DOTU_string.length, FIND, DOTU, NEWLINE - dq LIT, HELLA_string, LIT, HELLA_string.length, TELL, SPACE - dq LIT, HELLA_string, LIT, HELLA_string.length, FIND, DOTU, NEWLINE + dq READ_WORD, FIND, DOTU, NEWLINE + dq BRANCH, -8 * 5 dq TERMINATE segment readable writable -latest_entry dq DOTU_entry +latest_entry dq initial_latest_entry SPACE_string db 'SPACE' .length = $ - SPACE_string -- 2.39.2