\ input.v4 -- reading a line and splitting it into words and numbers. \ \ DECOMPOSITION.md 5.9: TIB >IN SPAN SOURCE BL EXPECT QUERY WORD ENCLOSE \ CONVERT NUMBER, and the comment words ( and \ of 5.15 (named PAREN and \ BACKSLASH here, since the text assembler reads those two characters as its \ own comments; the dictionary will give them their names). Part of the compiler \ capsule: it runs on the host node. Rests on core.v4. \ \ Constants the loader supplies: \ TIB byte address of the text input buffer, #TIB bytes long \ #TIB 1025: 1024 characters and a terminating zero, as v3 \ >IN word address of the variable: offset in TIB of the next character \ SPAN word address of the variable: how many characters the last \ EXPECT or QUERY read \ WBUF byte address of WORD's buffer, 64 bytes \ (P) word address of six cells of scratch for this file \ TIB >IN SPAN and BL are in-line: written in a definition they are literals. macro BL 32 endmacro \ ( -- baddr u ) the input buffer and how much of it is in use : SOURCE TIB SPAN a! @ -if P drop 0 P: ; \ ( baddr u -- ) read a line into u bytes at baddr, as v3's fgets did: at \ most u-1 characters, stopping after a new-line, which is taken but not \ stored; then a zero. A line of u-1 characters or more leaves what did not \ fit, its new-line included, to be read next. SPAN is the number of characters stored. With u = 0 \ nothing is read or stored; u < 0 does nothing and sets NODE-ERROR. : EXPECT -if OK drop drop NODE-ERROR b! -1 !b ; OK: if ZERO over push \ p n R: start L: -1 + if END \ room for the zero only push KEY dup -10 + if NL \ p c x R: start n drop over C! 1 + pop jump L NL: drop drop pop END: drop 0 over C! \ p pop - SPAN a! ! ; ZERO: drop drop 0 SPAN a! ! ; \ ( -- ) read a line into TIB and start at its beginning : QUERY TIB #TIB EXPECT 0 >IN a! ! ; \ ---- WORD ------------------------------------------------------------------ \ (P)+0 the delimiter, (P)+1 the length of the text in TIB. macro (WDELIM) (P) endmacro macro (WLEN) (P) 1 + endmacro : (LEFT) ( i -- i d ) dup (WLEN) a! @ - ; \ d < 0 while i is inside the text : (CH) ( i -- i x ) dup TIB + C@ (WDELIM) a! @ xor ; \ x = 0 at a delimiter : (SKIP) ( i -- i' ) \ past delimiters L: (LEFT) -if E drop (CH) if S drop ; S: drop 1 + jump L E: drop ; : (SCAN) ( i -- i' ) \ up to a delimiter L: (LEFT) -if E drop (CH) if E drop 1 + jump L E: drop ; \ ( c -- baddr ) the next word of TIB delimited by c, as a counted string \ in WBUF with a zero after it. Leading delimiters are skipped; so, as in \ v3, are all those that follow the word. A word longer than 62 characters \ is cut to 62. At the end of the text the count is 0. : WORD 255 and (WDELIM) a! ! SPAN a! @ -if A drop 0 A: (WLEN) a! ! >IN a! @ -if B drop 0 B: (SKIP) dup push (SCAN) \ end R: start pop over over - \ end start len dup -63 + -if CAP drop jump FITS CAP: drop drop 62 FITS: dup WBUF C! dup push push TIB + WBUF 1 + pop CMOVE \ end R: len 0 pop WBUF + 1 + C! (SKIP) >IN a! ! WBUF ; \ ---- ENCLOSE --------------------------------------------------------------- \ (P)+0 the delimiter, (P)+1 the string's address. : (E?) ( i -- i k ) \ k: 0 at the end of the string, 1 at a delimiter, else 2 dup (WLEN) a! @ + C@ if END (WDELIM) a! @ xor if DEL drop 2 ; DEL: drop 1 ; END: drop 0 ; : (ESKIP) ( i -- i' ) L: (E?) -1 + if S drop ; S: drop 1 + jump L : (ESCAN) ( i -- i' ) L: (E?) -2 + if S drop ; S: drop 1 + jump L \ ( baddr c -- baddr n1 n2 n3 ) in the zero-terminated string at baddr: \ n1 the offset of the first character that is not c, n2 the offset of the \ first c after it, n3 the offset of the first character after that run of c. : ENCLOSE 255 and (WDELIM) a! ! dup (WLEN) a! ! 0 (ESKIP) dup (ESCAN) dup (ESKIP) ; \ ---- CONVERT and NUMBER ---------------------------------------------------- \ ( c -- n ) the value of the digit c, 0 .. 35, in either case; -1 if none : (DIGIT) dup -48 + -if GE0 drop drop -1 ; GE0: drop dup -58 + -if GT9 drop -48 + ; GT9: drop dup -65 + -if GEA drop drop -1 ; GEA: drop dup -91 + -if GTZ drop -55 + ; GTZ: drop dup -97 + -if GEa drop drop -1 ; GEa: drop dup -123 + -if GTz drop -87 + ; GTz: drop drop -1 ; \ ( d1 baddr1 -- d2 baddr2 ) FORTH-79: the characters from baddr1 + 1 on are \ taken as digits in the current BASE, each accumulated into the double after \ it is multiplied by BASE, until one is not a digit; baddr2 is its address. \ (P)+2 holds the digit while the double is multiplied and (P)+5 the address, \ so nothing waits on the return stack across the calls. : CONVERT L: 1 + dup (P) 5 + a! ! C@ (DIGIT) \ lo hi n -if DIG drop (P) 5 + a! @ ; DIG: dup (BASE) - -if BIG drop (P) 2 + a! ! \ lo hi (BASE) UM* drop \ lo hi*base SWAP (BASE) UM* \ hi*base plo phi push SWAP pop + \ plo hi' (P) 2 + a! @ 0 D+ (P) 5 + a! @ jump L BIG: drop drop (P) 5 + a! @ ; \ ( baddr -- d ) FORTH-79: the counted string at baddr as a signed double in \ the current BASE; it may begin with a minus sign. If it is empty, is only \ a sign, or holds anything that is not a digit, the result is 0 and \ NODE-ERROR is set. The character after the string must not be a digit \ (WORD puts a zero there); if it is, that too is reported as an error. (P)+3 the address of its last character, (P)+4 the sign. : NUMBER dup C@ if ERR2 over + (P) 3 + a! ! \ baddr dup 1 + C@ -45 + if NEG drop 0 (P) 4 + a! ! jump GO NEG: drop -1 (P) 4 + a! ! 1 + dup (P) 3 + a! @ xor if ERR2 drop GO: push 0 0 pop CONVERT \ lo hi baddr2 (P) 3 + a! @ 1 + xor if FINE drop drop drop jump ERR0 FINE: drop (P) 4 + a! @ if POS drop jump DNEGATE POS: drop ; ERR2: drop drop ERR0: NODE-ERROR b! -1 !b 0 0 ; \ ---- comments (5.15) ------------------------------------------------------- \ PAREN skips to the closing parenthesis; BACKSLASH skips the rest of the line. : PAREN 41 WORD drop ; : BACKSLASH SPAN a! @ >IN a! ! ;