;; vim: syntax=fasm
-format ELF64 executable
+include "uefi.asm"
;; "Syscalls" {{{
;;
;; 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
}
;; }}}
.start:
}
-segment readable executable
-
-entry main
+section '.text' code readable executable
include "impl.asm" ; Misc. subroutines
include "bootstrap.asm" ; Forth words encoded in Assembly
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]
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
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
;; 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'
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 characters can be read.
-;;
-;; [TODO] We want to be able to use this when reading from buffers (e.g. in
-;; INTERPRET-STRING) too!
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, '"'
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.
dq LIT, input_buffer_length
dq EXIT
-segment readable writable
+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
;; 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 ?
here dq here_top
here_top rq $4000
-;; Pointer to input buffer and its length. Used as local variable in
-;; INTERPRET-STRING (see bootstrap.asm). [TODO] The code organization is a bit
-;; awkward here.
-input_buffer dq ?
-input_buffer_length dq ?
-
;; Return stack
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.
projects / rrq / jonasforth.git / blobdiff