From: Jonas Hvid Date: Sat, 16 Nov 2019 20:24:30 +0000 (+0100) Subject: Add somewhat working hello world X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=8c833141e36f00610bee5d20d058815423533b57;p=rrq%2Fjonasforth.git Add somewhat working hello world We exit by segfaulting, which is not very elegant. --- diff --git a/main.asm b/main.asm index e95d9fd..c5758d8 100644 --- a/main.asm +++ b/main.asm @@ -16,7 +16,7 @@ macro next { ;; register RBP. macro pushr x { sub rbp, 8 - mov [rbp], x + mov qword [rbp], x } macro popr x { mov x, [rbp] @@ -25,13 +25,73 @@ macro popr x { segment readable executable -start: - ;; Initialize return stack - mov rbp, return_stack_top +main: + cld ; Clear direction flag so LODSQ does the right thing. + mov rbp, return_stack_top ; Initialize return stack - jmp $ + mov rsi, program + next -segment readable +program: + dq HELLO + +;; 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: + 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 codeword 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: + popr rsi + next + +EMIT: + dq .start +.start: + pushr rsi + pushr rax + mov rax, 1 + mov rdi, 1 + lea rsi, [rsp] + mov rdx, 1 + syscall + add rsp, 8 + popr rax + popr rsi + next + +PUSH_HELLO_CHARS: + dq .start +.start: + push $A + push 'o' + push 'l' + push 'l' + push 'e' + push 'H' + next + +HELLO: + dq docol + dq PUSH_HELLO_CHARS + dq EMIT + dq EMIT + dq EMIT + dq EMIT + dq EMIT + dq EMIT + dq exit + +PROGRAM: + dq docol + dq HELLO + dq HELLO + dq HELLO + dq exit segment readable writable