X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=main.asm;h=a670b343e99c1a1f0154f0eab083ef6eb1e6cc1a;hb=95f71309628ccb9339cf43fb2326ab506bd5ae04;hp=538039b5ab29b0cd402d26105e3df89d3c5f2424;hpb=a856c7d5b35de1b48bdd948186ec4a03f7c3685c;p=rrq%2Fjonasforth.git

diff --git a/main.asm b/main.asm
index 538039b..a670b34 100644
--- a/main.asm
+++ b/main.asm
@@ -195,9 +195,14 @@ 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
@@ -207,6 +212,23 @@ 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'
@@ -387,10 +409,14 @@ 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
@@ -420,6 +446,40 @@ 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.
@@ -487,6 +547,8 @@ forth_asm EQL, '='
   next
 
 forth MAIN, 'MAIN'
+  dq SYSCODE
+  dq INTERPRET_STRING
   dq INTERPRET
   dq BRANCH, -8 * 2
   dq TERMINATE
@@ -505,6 +567,19 @@ 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
+
 segment readable writable
 
 ;; The LATEST variable holds a pointer to the word that was last added to the
@@ -516,6 +591,12 @@ 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 ?
@@ -538,3 +619,12 @@ here_top rq $4000
 ;; 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.
+sysf file 'sys.f'
+sysf.len = $ - sysf
+