FAST Forth Native-Language Embedded Computers

Scr # 501
0 \ begin line editor ( 16 5 91 CRC 8:25 )
1 FORTH DEFINITIONS ( DEBUG ) FORGET TASK
2 FORTH DEFINITIONS ( : TASK ; ) BASE F@ DECIMAL
3 SEQ BELL 1 C, CTL G C,
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5 ' (EXPECT) 'EXPECT F!
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7 VOCABULARY EXPECTING IMMEDIATE EXPECTING DEFINITIONS
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9 BLK F@ DUP 1+ SWAP 6 + THRU \ HERE FIRST OVER - ERASE
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11 ' LNED ' EXPECT F !
12 HERE FENCE F! BASE F! : TASK ; EDITOR FLUSH
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Scr # 502
0 \ line editor: variables, constants ( 25 11 91 CRC 13:44 )
1 0 VARIABLE CURS \ line cursor
2 0 VARIABLE BUF \ holding buffer
3 0 VARIABLE SIZE \ size of line already in buffer
4 1 VARIABLE PLACEF \ are we inserting or replacing?
5 0 VARIABLE NXTLN \ pointer to next line to place
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7 10 CONSTANT STRINGS \ number of back strings saved
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9 CREATE STRARRAY STRINGS 4* ALLOT \ pointer array
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11 ' QUERY 5 + C@ CONSTANT STRSIZE \ *very* implementation specific
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Scr # 503
0 \ line editor: makstrs, up dn history ( 25 11 91 CRC 13:47 )
1 : MAKESTRS \ construct the string buffer at compile time.
2 STRINGS 0 DO HERE DUP STRARRAY I 4* + F!
3 STRSIZE 1+ DUP ALLOT ERASE LOOP ;
4 MAKESTRS STRARRAY NXTLN F!
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6 : UP 4 NXTLN +! NXTLN F@ STRARRAY - 4/
7 STRINGS = IF STRARRAY NXTLN F! THEN ;
8
9 : DN NXTLN F@ STRARRAY \ down one in the string buffer
10 = IF [ STRARRAY STRINGS 4* + ] LITERAL NXTLN F! THEN
11 -4 NXTLN+! ;
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Scr # 504
0 \ line editor: redraw, history access ( 25 11 91 CRC 13:47 )
1 FORTH DEFINITIONS
2 : HISTORY EXPECTING STRINGS 0 DO DN NXTLN F@ F@
3 COUNT DUP IF CR I 4 .R SPACE THEN TYPE LOOP SPACE ;
4 : HIST HISTORY ;
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6 EXPECTING DEFINITIONS
7 :REDRAW\ --- I re-display the line from cursor
8 ERL BUFF@ CURS F@ + SIZE F@ CURSF@ -
9 -DUP IF DUP >R TYPE SPACE
10 R> 1+ 0 DO LEFT LOOP
11 ELSE SPACE LEFT DROP THEN ;
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13 : STORESTR \ --- I store string in array
14 BUFF@ NXTLN F@ F@ 1+ SIZE F@ 2DUP SWAP 1- C! CMOVE;
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Forth Dimensions 13
playing each line in it. Since
the word walks through the
ring buffer exactly the number
of times that there are
entries, the pointer is left
back in its starting position.
This code depends on the
word TYPE dropping its two
arguments when presented
with a count of zero.
REDRAW uses the terminal-specific
operator LEFT
to move the cursor left one
place on the screen. The
Atari ST screen emulates
the VT-52 terminal, and the
present cursor position cannot
be read by the application.
Other implementations
may be possible where the
terminal code permits reading
the cursor position.
REDRAW redisplays the line
from the current cursor position
out to the right end of
the line. An extra space is
emitted in case the most
recent keystroke deleted a
character in the line.
STORESTR (bottom of
screen 504) and GETSTR
move strings between the
edit buffer and the string
array. STORESTRstores the
count (from SIZE) in the
first byte of the array entry,
and GETSTRuses the count
to determine the length of
the string to be moved into
the edit buffer.
LEFT and RIGHT, on
screen 505, move the cursor
one space to the left or
right, if possible. If the cursor
is already at the end of
the line, a warning bell is
emitted instead. These two
words use their eponymous
cursor control words to
move the screen cursor appropriately.
They are activated
by the appropriate
cursor-control arrow key.
DEL, on line ten, deletes
the character under
the current cursor location.
Line 11 does the actual
deletion, culminating in the
CMOVE at the end. Line 12
March 1994 April