X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=main.asm;h=4ed478d0743f7f75d584f2632cc377e454fa98f8;hb=55d4cc10bbfa7bc445948b222b6a72d2d4b127a2;hp=ae3f9913eae15ea9f26a86c1b3d04a05215e2a8c;hpb=055f2efc3011a2102125cd0001adcff1cc6feab9;p=rrq%2Fjonasforth.git diff --git a/main.asm b/main.asm index ae3f991..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 } ;; }}} @@ -87,23 +123,17 @@ macro forth_asm label, name, immediate { .start: } -;; Define a Forth word that is implemented in Forth. (The body will be a list of -;; 'dq' statements.) -macro forth label, name, immediate { - header label, name, immediate - dq DOCOL -} - -segment readable executable - -entry main +section '.text' code readable executable -include "impl.asm" +include "impl.asm" ; Misc. subroutines +include "bootstrap.asm" ; Forth words encoded in Assembly 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] @@ -201,21 +231,14 @@ forth_asm EMIT, 'EMIT' popr rsi next -;; Prints a newline to standard output. -forth NEWLINE, 'NEWLINE' - dq LIT, $A - dq EMIT - dq EXIT - -;; Prints a space to standard output. -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 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 @@ -225,6 +248,23 @@ forth_asm READ_WORD, 'READ-WORD' mov rsi, [.rsi] next +.from_buffer: + ;; Reading from buffer + mov [.rsi], rsi + + mov rsi, [input_buffer] + mov rcx, [input_buffer_length] + + call pop_word + + 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 + + mov rsi, [.rsi] + next + ;; Takes a string on the stack and replaces it with the decimal number that the ;; string represents. forth_asm PARSE_NUMBER, 'PARSE-NUMBER' @@ -238,11 +278,6 @@ forth_asm PARSE_NUMBER, 'PARSE-NUMBER' push rax ; Result next -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. forth_asm TELL, 'TELL' @@ -259,9 +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' @@ -297,55 +330,6 @@ forth_asm NOT_, 'NOT' 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. -forth INTERPRET, 'INTERPRET' - ;; Read word - dq READ_WORD - 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 @@ -459,45 +443,21 @@ forth_asm TIMESMOD, '/MOD' 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 +;; 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, '"' @@ -517,6 +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. @@ -550,30 +544,6 @@ forth_asm CREATE, 'CREATE' 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 @@ -608,11 +578,40 @@ forth_asm EQL, '=' next forth MAIN, 'MAIN' + dq SYSCODE + dq INTERPRET_STRING dq INTERPRET dq BRANCH, -8 * 2 dq TERMINATE -segment readable writable +;; Built-in variables: + +forth STATE, 'STATE' + dq LIT, var_STATE + dq EXIT + +forth LATEST, 'LATEST' + dq LIT, latest_entry + dq EXIT + +forth HERE, 'HERE' + dq LIT, here + dq EXIT + +forth SYSCODE, 'SYSCODE' + dq LIT, sysf + dq LIT, sysf.len + dq EXIT + +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 @@ -623,6 +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 ? @@ -645,3 +650,10 @@ here_top rq $4000 ;; Return stack rq $2000 return_stack_top: + +;; 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. +sysf file 'sys.f' +sysf.len = $ - sysf +