X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=main.asm;h=4ed478d0743f7f75d584f2632cc377e454fa98f8;hb=a0c4c60159c79c8d9af3d08e01bacfa354232c3b;hp=c9a7fc42acc1d9deb022010648f9c36c1aab30ee;hpb=fbd07fa0c1aaad0cca46f9b1fc4839e053454f03;p=rrq%2Fjonasforth.git diff --git a/main.asm b/main.asm index c9a7fc4..4ed478d 100644 --- a/main.asm +++ b/main.asm @@ -1,6 +1,6 @@ ;; vim: syntax=fasm -format ELF64 executable +include "uefi.asm" ;; "Syscalls" {{{ @@ -22,10 +22,46 @@ format ELF64 executable ;; ;; Clobbers: RAX, RCX, R11, RDI, RSI macro sys_print_string { - mov rax, 1 - mov rdi, 1 - mov rsi, rcx - syscall + push r8 + push r9 + push r10 + + call uefi_print_string + + pop r10 + pop r9 + pop r8 +} + +;; Read a character from the user into the given buffer. +;; +;; Input: +;; - RSI = Character buffer +;; +;; Output: +;; - BYTE [RSI] = Character +;; +;; Clobbers: RAX, RCX, R11, RDI, RSI, RDX +macro sys_read_char { + push rbx + push r8 + push r9 + push r10 + push r15 + + mov rcx, rsi + call uefi_read_char + + pop r15 + pop r10 + pop r9 + pop r8 + pop rbx +} + +macro sys_terminate code { + mov rax, code + call uefi_terminate } ;; }}} @@ -87,9 +123,7 @@ macro forth_asm label, name, immediate { .start: } -segment readable executable - -entry main +section '.text' code readable executable include "impl.asm" ; Misc. subroutines include "bootstrap.asm" ; Forth words encoded in Assembly @@ -98,6 +132,8 @@ main: cld ; Clear direction flag so LODSQ does the right thing. mov rbp, return_stack_top ; Initialize return stack + call uefi_initialize + mov rax, MAIN jmp qword [rax] @@ -195,9 +231,14 @@ forth_asm EMIT, 'EMIT' popr rsi next -;; 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 a word and push it onto the stack as a pointer and a size. The pointer +;; is valid until the next call to READ_WORD. forth_asm READ_WORD, 'READ-WORD' + ;; Are we reading from user input or from the input buffer? + cmp [input_buffer], 0 + jne .from_buffer + + ;; Reading user input mov [.rsi], rsi call read_word @@ -207,23 +248,21 @@ forth_asm READ_WORD, 'READ-WORD' mov rsi, [.rsi] next -;; Read a word from a buffer. Expects (buffer buffer-length) on the stack. -;; Updates buffer and buffer-length, such that the word has been removed from -;; the buffer. Appends (word-buffer word-buffer-length) to the stack. -forth_asm POP_WORD, 'POP-WORD' - pushr rsi +.from_buffer: + ;; Reading from buffer + mov [.rsi], rsi - pop rcx ; Length - pop rsi ; Buffer + mov rsi, [input_buffer] + mov rcx, [input_buffer_length] call pop_word - push rsi ; Updated buffer - push rcx ; Length of updated buffer - push rdi ; Word buffer - push rdx ; Length of word buffer + mov [input_buffer], rsi ; Updated buffer + mov [input_buffer_length], rcx ; Length of updated buffer + push rdi ; Word buffer + push rdx ; Length of word buffer - popr rsi + mov rsi, [.rsi] next ;; Takes a string on the stack and replaces it with the decimal number that the @@ -255,9 +294,7 @@ forth_asm TELL, 'TELL' ;; Exit the program cleanly. forth_asm TERMINATE, 'TERMINATE' - mov rax, $3C - mov rdi, 0 - syscall + sys_terminate 0 ;; Duplicate a pair of elements. forth_asm PAIRDUP, '2DUP' @@ -406,20 +443,21 @@ forth_asm TIMESMOD, '/MOD' push rdx ; a % b next -;; Read user input until next " character is found. Push a string containing the +;; Read 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. +;; until the next call to S" and that no more than 255 characters can be read. forth_asm READ_STRING, 'S"' + ;; If the input buffer is set, we should read from there instead. + cmp [input_buffer], 0 + jne read_string_buffer + push rsi mov [.length], 0 .read_char: - mov rax, 0 - mov rdi, 0 mov rsi, .char_buffer - mov rdx, 1 - syscall + sys_read_char mov al, [.char_buffer] cmp al, '"' @@ -439,6 +477,40 @@ forth_asm READ_STRING, 'S"' next +read_string_buffer: + push rsi + + ;; We borrow READ_STRING's buffer. They won't mind. + mov [READ_STRING.length], 0 + +.read_char: + mov rbx, [input_buffer] + mov al, [rbx] + cmp al, '"' + je .done + + mov rdx, READ_STRING.buffer + add rdx, [READ_STRING.length] + mov [rdx], al + inc [READ_STRING.length] + + inc [input_buffer] + dec [input_buffer_length] + + jmp .read_char + +.done: + pop rsi + + ;; Skip closing " + inc [input_buffer] + dec [input_buffer_length] + + push READ_STRING.buffer + push [READ_STRING.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. @@ -506,6 +578,8 @@ forth_asm EQL, '=' next forth MAIN, 'MAIN' + dq SYSCODE + dq INTERPRET_STRING dq INTERPRET dq BRANCH, -8 * 2 dq TERMINATE @@ -529,7 +603,15 @@ forth SYSCODE, 'SYSCODE' dq LIT, sysf.len dq EXIT -segment readable writable +forth INPUT_BUFFER, 'INPUT-BUFFER' + dq LIT, input_buffer + dq EXIT + +forth INPUT_LENGTH, 'INPUT-LENGTH' + dq LIT, input_buffer_length + dq EXIT + +section '.data' 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 @@ -540,6 +622,12 @@ latest_entry dq initial_latest_entry ;; it is compiling. var_STATE dq 0 +;; The interpreter can read either from standard input or from a buffer. When +;; input-buffer is set (non-null), words like READ-WORD and S" will use this +;; buffer instead of reading user input. +input_buffer dq 0 +input_buffer_length dq 0 + FIND.rsi dq ? READ_WORD.rsi dq ? @@ -563,8 +651,6 @@ here_top rq $4000 rq $2000 return_stack_top: -segment readable - ;; We store some Forth code in sys.f that defined common words that the user ;; would expect to have available at startup. To execute these words, we just ;; include the file directly in the binary, and then interpret it at startup.