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@ -1,21 +1,11 @@
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|||||||
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Be sure to read "usage.txt" for a guide to Collapse OS' Forth.
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*** Glossary ***
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Stack notation: "<stack before> -- <stack after>". Rightmost is top of stack
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Stack notation: "<stack before> -- <stack after>". Rightmost is top of stack
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(TOS). For example, in "a b -- c d", b is TOS before, d is TOS after. "R:" means
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(TOS). For example, in "a b -- c d", b is TOS before, d is TOS after. "R:" means
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that the Return Stack is modified. "I:" prefix means "IMMEDIATE", that is, that
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that the Return Stack is modified. "I:" prefix means "IMMEDIATE", that is, that
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this stack transformation is made at compile time.
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this stack transformation is made at compile time.
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|
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DOES>: Used inside a colon definition that itself uses CREATE, DOES> transforms
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that newly created word into a "does cell", that is, a regular cell ( when
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called, puts the cell's addr on PS), but right after that, it executes words
|
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that appear after the DOES>.
|
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|
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"does cells" always allocate 4 bytes (2 for the cell, 2 for the DOES> link) and
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there is no need for ALLOT in colon definition.
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At compile time, colon definition stops processing words when reaching the
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DOES>.
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Example: ": CONSTANT CREATE HERE @ ! DOES> @ ;"
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Word references (wordref): When we say we have a "word reference", it's a
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Word references (wordref): When we say we have a "word reference", it's a
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pointer to a words *code link*. For example, the label "PLUS:" in this unit is a
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pointer to a words *code link*. For example, the label "PLUS:" in this unit is a
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word reference. Why not refer to the beginning of the word struct? Because we
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word reference. Why not refer to the beginning of the word struct? Because we
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@ -54,20 +44,6 @@ IMMEDIATE -- Flag the latest defined word as immediate.
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LITN n -- Write number n as a literal.
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LITN n -- Write number n as a literal.
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VARIABLE c -- Creates cell x with 2 bytes allocation.
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VARIABLE c -- Creates cell x with 2 bytes allocation.
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Compilation vs meta-compilation. When you compile a word with "[COMPILE] foo",
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its straightforward: It writes down to HERE wither the address of the word or
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a number literal.
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When you *meta* compile, it's a bit more mind blowing. It fetches the address
|
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of the word specified by the caller, then writes that number as a literal,
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followed by a reference to ",".
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Example: ": foo [COMPILE] bar;" is the equivalent of ": foo bar ;" if bar is
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not an immediate. However, ": foo COMPILE bar ;" is the equivalent of
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": foo ['] bar , ;". Got it?
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Meta-compile only works with real words, not number literals.
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*** Flow ***
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*** Flow ***
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Note about flow words: flow words can only be used in definitions. In the
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Note about flow words: flow words can only be used in definitions. In the
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INTERPRET loop, they don't have the desired effect because each word from the
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INTERPRET loop, they don't have the desired effect because each word from the
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@ -156,32 +132,6 @@ SLEN a -- n Push length of str at a.
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*** I/O ***
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*** I/O ***
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A little word about inputs. There are two kind of inputs: direct and buffered.
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As a general rule, we read line in a buffer, then feed words in it to the
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interpreter. That's what "WORD" does. If it's at the End Of Line, it blocks and
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wait until another line is entered.
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KEY input, however, is direct. Regardless of the input buffer's state, KEY will
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return the next typed key.
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PARSING AND BOOTSTRAP: Parsing number literal is a very "core" activity of
|
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Forth, and therefore generally seen as having to be implemented in native code.
|
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However, Collapse OS' Forth supports many kinds of literals: decimal, hex, char,
|
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binary. This incurs a significant complexity penalty.
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|
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What if we could implement those parsing routines in Forth? "But it's a core
|
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routine!" you say. Yes, but here's the deal: at its native core, only decimal
|
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parsing is supported. It lives in the "(parsed)" word. The interpreter's main
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loop is initially set to simply call that word.
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|
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However, in core.fs, "(parsex)", "(parsec)" and "(parseb)" are implemented, in
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Forth, then "(parse)", which goes through them all is defined. Then, "(parsef)",
|
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which is the variable in which the interpreter's word pointer is set, is
|
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updated to that new "(parse)" word.
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This way, we have a full-featured (and extensible) parsing with a tiny native
|
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core.
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(parse) a -- n Parses string at a as a number and push the result
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(parse) a -- n Parses string at a as a number and push the result
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in n as well as whether parsing was a success in f
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in n as well as whether parsing was a success in f
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(false = failure, true = success)
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(false = failure, true = success)
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@ -193,11 +143,15 @@ core.
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number parsing. By default, (parse).
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number parsing. By default, (parse).
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(print) a -- Print string at addr a.
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(print) a -- Print string at addr a.
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. n -- Print n in its decimal form
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. n -- Print n in its decimal form
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.X n -- Print n in its hexadecimal form. In hex, numbers
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.x n -- Print n's LSB in hex form. Always 2 characters.
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.X n -- Print n in hex form. Always 4 characters. Numbers
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are never considered negative. "-1 .X" --> ffff
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." xxx" -- *I* Compiles string literal xxx followed by a call
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." xxx" -- *I* Compiles string literal xxx followed by a call
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to (print)
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to (print)
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are never considered negative. "-1 .X -> ffff"
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C< -- c Read one char from buffered input.
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C< -- c Read one char from buffered input.
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DUMP n a -- Prints n bytes at addr a in a hexdump format.
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Prints in chunks of 8 bytes. Doesn't do partial
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lines. Output is designed to fit in 32 columns.
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EMIT c -- Spit char c to output stream
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EMIT c -- Spit char c to output stream
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IN> -- a Address of variable containing current pos in input
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IN> -- a Address of variable containing current pos in input
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buffer.
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buffer.
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@ -1,6 +1,6 @@
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TARGETS = runbin/runbin forth/forth
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TARGETS = runbin/runbin forth/forth
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# Those Forth source files are in a particular order
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# Those Forth source files are in a particular order
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FORTHSRCS = core.fs print.fs str.fs parse.fs readln.fs fmt.fs z80a.fs
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FORTHSRCS = core.fs cmp.fs print.fs str.fs parse.fs readln.fs fmt.fs z80a.fs
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FORTHSRC_PATHS = ${FORTHSRCS:%=../forth/%} forth/run.fs
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FORTHSRC_PATHS = ${FORTHSRCS:%=../forth/%} forth/run.fs
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OBJS = emul.o libz80/libz80.o
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OBJS = emul.o libz80/libz80.o
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SLATEST = ../tools/slatest
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SLATEST = ../tools/slatest
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38
forth/cmp.fs
Normal file
38
forth/cmp.fs
Normal file
@ -0,0 +1,38 @@
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( Words useful for complex comparison operations )
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( n1 -- n1 true )
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: <>{ 1 ;
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( n1 f -- f )
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: <>} SWAP DROP ;
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: _|&
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( n1 n2 cell )
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>R >R DUP R> R> ( n1 n1 n2 cell )
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@ EXECUTE ( n1 f )
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;
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( n1 f n2 -- n1 f )
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: _|
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CREATE , DOES>
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( n1 f n2 cell )
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ROT IF 2DROP 1 EXIT THEN ( n1 true )
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_|&
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;
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: _&
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CREATE , DOES>
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( n1 f n2 cell )
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ROT NOT IF 2DROP 0 EXIT THEN ( n1 true )
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_|&
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;
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( All words below have this signature:
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n1 f n2 -- n1 f )
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' = _| |=
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' = _& &=
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' > _| |>
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' > _& &>
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' < _| |<
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' < _& &<
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64
forth/fmt.fs
64
forth/fmt.fs
@ -1,7 +1,6 @@
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( requires core, parse )
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( requires core, parse )
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( TODO FORGET this word )
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: _
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: PUSHDGTS
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999 SWAP ( stop indicator )
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999 SWAP ( stop indicator )
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DUP 0 = IF '0' EXIT THEN ( 0 is a special case )
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DUP 0 = IF '0' EXIT THEN ( 0 is a special case )
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BEGIN
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BEGIN
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@ -16,7 +15,7 @@
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( that "0 1 -" thing is because we don't parse negative
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( that "0 1 -" thing is because we don't parse negative
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number correctly yet. )
|
number correctly yet. )
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DUP 0 < IF '-' EMIT 0 1 - * THEN
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DUP 0 < IF '-' EMIT 0 1 - * THEN
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PUSHDGTS
|
_
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BEGIN
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BEGIN
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DUP '9' > IF DROP EXIT THEN ( stop indicator, we're done )
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DUP '9' > IF DROP EXIT THEN ( stop indicator, we're done )
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EMIT
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EMIT
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@ -25,24 +24,53 @@
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: ? @ . ;
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: ? @ . ;
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|
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: PUSHDGTS
|
: _
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999 SWAP ( stop indicator )
|
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DUP 0 = IF '0' EXIT THEN ( 0 is a special case )
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BEGIN
|
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DUP 0 = IF DROP EXIT THEN
|
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16 /MOD ( r q )
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SWAP ( r q )
|
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DUP 9 > IF 10 - 'a' +
|
DUP 9 > IF 10 - 'a' +
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ELSE '0' + THEN ( q d )
|
ELSE '0' + THEN
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SWAP ( d q )
|
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AGAIN
|
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;
|
;
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||||||
|
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: .X ( n -- )
|
( For hex display, there are no negatives )
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( For hex display, there are no negatives )
|
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PUSHDGTS
|
: .x
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|
256 MOD ( ensure < 0x100 )
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|
16 /MOD ( l h )
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|
_ EMIT ( l )
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|
_ EMIT
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|
;
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||||||
|
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||||||
|
: .X
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||||||
|
256 /MOD ( l h )
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||||||
|
.x .x
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|
;
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||||||
|
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||||||
|
( a -- a+8 )
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|
: _
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|
DUP ( save for 2nd loop )
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|
':' EMIT DUP .x SPC
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|
4 0 DO
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|
DUP @
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|
256 /MOD SWAP
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||||||
|
.x .x
|
||||||
|
SPC
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||||||
|
2 +
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||||||
|
LOOP
|
||||||
|
DROP
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||||||
|
8 0 DO
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||||||
|
DUP C@
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||||||
|
DUP <>{ 0x20 &< 0x7e |> <>}
|
||||||
|
IF DROP '.' THEN
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||||||
|
EMIT
|
||||||
|
1 +
|
||||||
|
LOOP
|
||||||
|
LF
|
||||||
|
;
|
||||||
|
|
||||||
|
( n a -- )
|
||||||
|
: DUMP
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||||||
|
LF
|
||||||
BEGIN
|
BEGIN
|
||||||
DUP 'f' > IF DROP EXIT THEN ( stop indicator, we're done )
|
OVER 1 < IF DROP EXIT THEN
|
||||||
EMIT
|
_
|
||||||
|
SWAP 8 - SWAP
|
||||||
AGAIN
|
AGAIN
|
||||||
;
|
;
|
||||||
|
88
usage.txt
Normal file
88
usage.txt
Normal file
@ -0,0 +1,88 @@
|
|||||||
|
Collapse OS usage guide
|
||||||
|
|
||||||
|
This document is not meant to be an introduction to Forth, but to instruct the
|
||||||
|
user about the peculiarities of this Forth implemenation. Be sure to refer to
|
||||||
|
dictionary.txt for a word reference.
|
||||||
|
|
||||||
|
*** DOES>
|
||||||
|
|
||||||
|
Used inside a colon definition that itself uses CREATE, DOES> transforms that
|
||||||
|
newly created word into a "does cell", that is, a regular cell ( when called,
|
||||||
|
puts the cell's addr on PS), but right after that, it executes words that appear
|
||||||
|
after the DOES>.
|
||||||
|
|
||||||
|
"does cells" always allocate 4 bytes (2 for the cell, 2 for the DOES> link) and
|
||||||
|
there is no need for ALLOT in colon definition.
|
||||||
|
|
||||||
|
At compile time, colon definition stops processing words when reaching the
|
||||||
|
DOES>.
|
||||||
|
|
||||||
|
Example: ": CONSTANT CREATE HERE @ ! DOES> @ ;"
|
||||||
|
|
||||||
|
*** Compilation vs meta-compilation
|
||||||
|
|
||||||
|
Compilation vs meta-compilation. When you compile a word with "[COMPILE] foo",
|
||||||
|
its straightforward: It writes down to HERE wither the address of the word or
|
||||||
|
a number literal.
|
||||||
|
|
||||||
|
When you *meta* compile, it's a bit more mind blowing. It fetches the address
|
||||||
|
of the word specified by the caller, then writes that number as a literal,
|
||||||
|
followed by a reference to ",".
|
||||||
|
|
||||||
|
Example: ": foo [COMPILE] bar;" is the equivalent of ": foo bar ;" if bar is
|
||||||
|
not an immediate. However, ": foo COMPILE bar ;" is the equivalent of
|
||||||
|
": foo ['] bar , ;". Got it?
|
||||||
|
|
||||||
|
Meta-compile only works with real words, not number literals.
|
||||||
|
|
||||||
|
*** I/O
|
||||||
|
|
||||||
|
A little word about inputs. There are two kind of inputs: direct and buffered.
|
||||||
|
As a general rule, we read line in a buffer, then feed words in it to the
|
||||||
|
interpreter. That's what "WORD" does. If it's at the End Of Line, it blocks and
|
||||||
|
wait until another line is entered.
|
||||||
|
|
||||||
|
KEY input, however, is direct. Regardless of the input buffer's state, KEY will
|
||||||
|
return the next typed key.
|
||||||
|
|
||||||
|
PARSING AND BOOTSTRAP: Parsing number literal is a very "core" activity of
|
||||||
|
Forth, and therefore generally seen as having to be implemented in native code.
|
||||||
|
However, Collapse OS' Forth supports many kinds of literals: decimal, hex, char,
|
||||||
|
binary. This incurs a significant complexity penalty.
|
||||||
|
|
||||||
|
What if we could implement those parsing routines in Forth? "But it's a core
|
||||||
|
routine!" you say. Yes, but here's the deal: at its native core, only decimal
|
||||||
|
parsing is supported. It lives in the "(parsed)" word. The interpreter's main
|
||||||
|
loop is initially set to simply call that word.
|
||||||
|
|
||||||
|
However, in core.fs, "(parsex)", "(parsec)" and "(parseb)" are implemented, in
|
||||||
|
Forth, then "(parse)", which goes through them all is defined. Then, "(parsef)",
|
||||||
|
which is the variable in which the interpreter's word pointer is set, is
|
||||||
|
updated to that new "(parse)" word.
|
||||||
|
|
||||||
|
This way, we have a full-featured (and extensible) parsing with a tiny native
|
||||||
|
core.
|
||||||
|
|
||||||
|
*** Chained comparisons
|
||||||
|
|
||||||
|
The unit "cmp.fs" contains words to facilitate chained comparisons with a single
|
||||||
|
reference number. This allows, for example, to easily express "a == b or a == c"
|
||||||
|
or "a > b and a < c".
|
||||||
|
|
||||||
|
The way those chained comparison words work is that, unlike single comparison
|
||||||
|
operators, they don't have a "n1 n2 -- f" signature, but rather a "n1 f n2 -- n1
|
||||||
|
f" signature. That is, each operator "carries over" the reference number in
|
||||||
|
addition to the latest flag.
|
||||||
|
|
||||||
|
You open a chain with "<>{" and you close a chain with "<>}". Then, in between
|
||||||
|
those words, you can chain operators. For example, to check whether A == B or A
|
||||||
|
== C, you would write:
|
||||||
|
|
||||||
|
A <>{ B &= C |= <>}
|
||||||
|
|
||||||
|
The first operator must be of the "&" type because the chain starts with its
|
||||||
|
flag to true. For example, "<>{ <>}" yields true.
|
||||||
|
|
||||||
|
To check whether A is in between B and C inclusively, you would write:
|
||||||
|
|
||||||
|
A <>{ B 1 - &> C 1 + &< <>}
|
Loading…
Reference in New Issue
Block a user