X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;ds=sidebyside;f=main.asm;h=ae3f9913eae15ea9f26a86c1b3d04a05215e2a8c;hb=055f2efc3011a2102125cd0001adcff1cc6feab9;hp=8133cdc33b284a2ce2b3764df1c2304bbe40e9fa;hpb=89a6a52d6128a4f9ac3c7aa26fc0df111e4160db;p=rrq%2Fjonasforth.git

diff --git a/main.asm b/main.asm
index 8133cdc..ae3f991 100644
--- a/main.asm
+++ b/main.asm
@@ -1,5 +1,35 @@
+;; vim: syntax=fasm
+
 format ELF64 executable
 
+;; "Syscalls" {{{
+
+;; [NOTE] Volatile registers Linux (syscalls) vs UEFI
+;;
+;;   Linux syscalls: RAX, RCX, R11
+;;   UEFI:           RAX, RCX, R11, RDX, R8, R9, R10
+
+;; We are in the process of replacing our dependency on Linux with a dependency
+;; on UEFI. The following macros attempt to isolate what would be syscalls in
+;; Linux; thus, we will be able to replace these with UEFI-based implementations,
+;; and in theory we should expect the program to work.
+
+;; Print a string of a given length.
+;;
+;; Input:
+;; - RCX = Pointer to buffer
+;; - RDX = Buffer length
+;;
+;; Clobbers: RAX, RCX, R11, RDI, RSI
+macro sys_print_string {
+  mov rax, 1
+  mov rdi, 1
+  mov rsi, rcx
+  syscall
+}
+
+;; }}}
+
 ;; The code in this macro is placed at the end of each Forth word. When we are
 ;; executing a definition, this code is what causes execution to resume at the
 ;; next word in that definition.
@@ -37,7 +67,11 @@ macro header label, name, immediate {
 
 label#_entry:
   dq initial_latest_entry
-  dq 0
+  if immediate eq
+    db 0
+  else
+    db 1
+  end if
   db .string_end - ($ + 1)
   db name
   .string_end:
@@ -118,7 +152,7 @@ forth_asm FIND, 'FIND'
 ;; entry.
 forth_asm TCFA, '>CFA'
   pop rax
-  add rax, 16                   ; [rax] = length of name
+  add rax, 8 + 1                ; [rax] = length of name
   movzx rbx, byte [rax]
   inc rax
   add rax, rbx                  ; [rax] = codeword
@@ -157,11 +191,11 @@ forth_asm EXEC, 'EXEC'
 forth_asm EMIT, 'EMIT'
   pushr rsi
   pushr rax
-  mov rax, 1
-  mov rdi, 1
-  lea rsi, [rsp]
+
+  lea rcx, [rsp]
   mov rdx, 1
-  syscall
+  sys_print_string
+
   add rsp, 8
   popr rax
   popr rsi
@@ -194,8 +228,8 @@ forth_asm READ_WORD, 'READ-WORD'
 ;; Takes a string on the stack and replaces it with the decimal number that the
 ;; string represents.
 forth_asm PARSE_NUMBER, 'PARSE-NUMBER'
-  pop [parse_number.length]     ; Length
-  pop [parse_number.buffer]     ; String pointer
+  pop rcx     ; Length
+  pop rdi     ; String pointer
 
   push rsi
   call parse_number
@@ -212,17 +246,15 @@ forth READ_NUMBER, 'READ-NUMBER'
 ;; 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'
-  mov rbx, rsi
-  mov rcx, rax
+  pushr rax
+  pushr rsi
 
-  mov rax, 1
-  mov rdi, 1
-  pop rdx     ; Length
-  pop rsi     ; Buffer
-  syscall
+  pop rdx ; Length
+  pop rcx ; Buffer
+  sys_print_string
 
-  mov rax, rcx
-  mov rsi, rbx
+  popr rsi
+  popr rax
   next
 
 ;; Exit the program cleanly.
@@ -231,16 +263,6 @@ forth_asm TERMINATE, 'TERMINATE'
   mov rdi, 0
   syscall
 
-forth HELLO, 'HELLO'
-  dq LIT, 'H', EMIT
-  dq LIT, 'e', EMIT
-  dq LIT, 'l', EMIT
-  dq LIT, 'l', EMIT
-  dq LIT, 'o', EMIT
-  dq LIT, '!', EMIT
-  dq NEWLINE
-  dq EXIT
-
 ;; Duplicate a pair of elements.
 forth_asm PAIRDUP, '2DUP'
   pop rbx
@@ -264,8 +286,19 @@ forth_asm DROP, 'DROP'
   add rsp, 8
   next
 
+forth_asm NOT_, 'NOT'
+  pop rax
+  cmp rax, 0
+  jz .false
+.true:
+  push 0
+  next
+.false:
+  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. (TODO)
+;; the current STATE. It provides special handling for integers.
 forth INTERPRET, 'INTERPRET'
   ;; Read word
   dq READ_WORD
@@ -273,9 +306,23 @@ forth INTERPRET, 'INTERPRET'
   ;; Stack is (word length word length).
   dq FIND                       ; Try to find word
   dq DUP_
-  dq ZBRANCH, 8 * 8             ; Check if word is found
+  dq ZBRANCH, 8 * 22            ; Check if word is found
 
-  ;; Word is found, execute it
+  ;; - 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
@@ -284,10 +331,19 @@ forth INTERPRET, 'INTERPRET'
   dq EXEC
   dq EXIT
 
-  ;; No word is found, assume it is an integer literal
+  ;; - 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.
@@ -341,11 +397,9 @@ forth_asm DOTU, '.U'
   loop .flip
 
   ;; Print the buffer
-  mov rax, 1
-  mov rdi, 1
-  mov rsi, .buffer
+  mov rcx, .buffer
   mov rdx, [.printed_length]
-  syscall
+  sys_print_string
 
   ;; Restore RSI and continue execution
   pop rsi
@@ -365,6 +419,18 @@ forth_asm GET, '@'
   push rax
   next
 
+forth_asm PUT_BYTE, 'C!'
+  pop rbx
+  pop rax                       ; Value
+  mov [rbx], al
+  next
+
+forth_asm GET_BYTE, 'C@'
+  pop rax
+  movzx rax, byte [rax]
+  push rax
+  next
+
 ;; Add two integers on the stack.
 forth_asm PLUS, '+'
   pop rax
@@ -382,6 +448,17 @@ forth_asm MINUS, '-'
   push rbx
   next
 
+;; Given two integers a and b on the stack, pushes the quotient and remainder of
+;; division of a by b.
+forth_asm TIMESMOD, '/MOD'
+  pop rbx                       ; b
+  pop rax                       ; a
+  mov rdx, 0
+  div rbx
+  push rax                      ; a / b
+  push rdx                      ; a % b
+  next
+
 ;; Get the location of the STATE variable. It can be set with '!' and read with
 ;; '@'.
 forth STATE, 'STATE'
@@ -455,11 +532,10 @@ forth_asm CREATE, 'CREATE'
   mov [latest_entry], rdi       ; Update LATEST to point to this word
 
   add rdi, 8
-  mov rax, 0
-  mov [rdi], rax                ; Set immediate flag
+  mov [rdi], byte 0             ; Insert immediate flag
 
-  add rdi, 8
-  mov [rdi], rcx                ; Insert length
+  add rdi, 1
+  mov [rdi], byte cl            ; Insert length
 
   ;; Insert word string
   add rdi, 1
@@ -479,18 +555,59 @@ forth IMMEDIATE, 'IMMEDIATE', 1
   dq LIT, 1
   dq LATEST, GET
   dq LIT, 8, PLUS
-  dq PUT
+  dq PUT_BYTE
   dq EXIT
 
-;; Return 0 if the given word is not immediate.
+;; Given the address of a word, return 0 if the given word is not immediate.
 forth IS_IMMEDIATE, 'IMMEDIATE?'
-  dq FIND
   dq LIT, 8, PLUS
-  dq GET
+  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
+  next
+
+forth_asm ROT, 'ROT'
+  pop rax
+  pop rbx
+  pop rdx
+  push rax
+  push rdx
+  push rbx
+  next
+
+forth_asm PICK, 'PICK'
+  pop rax
+  lea rax, [rsp + 8 * rax]
+  mov rax, [rax]
+  push rax
+  next
+
+forth_asm EQL, '='
+  pop rax
+  pop rbx
+  cmp rax, rbx
+  je .eq
+.noteq:
+  push 0
+  next
+.eq:
+  push 1
+  next
+
 forth MAIN, 'MAIN'
-  dq HELLO
   dq INTERPRET
   dq BRANCH, -8 * 2
   dq TERMINATE
@@ -523,7 +640,7 @@ DOTU.printed_length dq ?
 
 ;; Reserve space for compiled words, accessed through HERE.
 here dq here_top
-here_top rq $2000
+here_top rq $4000
 
 ;; Return stack
 rq $2000