Pascal News

61
trsl ~~RAY [t •• maxlengthl OF treept
119 VAR 179
120 temp: treept: 180
121
62
END;
122
63 newcharsetl ARRAY [alphabet1 OF newchar:
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64 stactc: newchar;
124
65
66
61 PROCEDURE get_char:
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126
127
68
128
69 BEGIN
129
70
REPEAT num_in_cnars:= num_ln-ehars + t;
no
71 UNTIL eof(ln_flle) OR (ord(1n-flh-.) 0)
III
72 ENDtGET_CHAR);
1J2
73
III
74
134
75 PROCEDURE fIll_tally:
135
H. (Scan the file the first tIme and get a character count on
U6
77 WhIch to maKe the new Huffman character set.)
78
117
U8
79 VAR 139
80 count: integer:
140
81
141
82 BEGIN
142
83 reset(1n_file 1I
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84
FOR count := 'ftlnchar.J'O 127 DC?,
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85
WIrH tallylcountl'DO .
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86
BEGIN marKed: e falsel
1= 0
146
87 IF NOr eol(1n_file)
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88
THEN
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BEGIN
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90
IJet_char:
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91
WHILE NOT eofCin_file) DO
1!>1
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8EGIN
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93
If' ord(1n_flle-) < minchar THEN
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94
BEGU
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95
writelnCtty, 'Bad character in input!·~·, ordC
l!>5
96
in_file-» :
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97
GOTO 13
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98
END:
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99
tallylord(1n_Hle-)]. num_of 1= tally[ordCin_flle-.>
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100
]. nu .._of + 1;
1&0
101
get_Char I
lot
102
END
102
103
END
163
104 END (FILL_T~LLr):
Ib4
105
Ib5
106
166
101 PROCEDURE exchangeCVAR x, Y: integer):
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108
t&8
109 VAR 11>9
110 temp: integer:
110
111
111
112 BEGTN temp := x, x := VI V := temp E~D (EXCHANGE):
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113
173
114
114
115 PROCEDURE .. aKe_new_chars:
115
116 (~aKe the Huffman Characters based on the character frequencies
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117 of the file.)
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118
178
poSl, pos2, cOQnt: inteqer:
done, trl, tr2: boolean:
PROCE~URE 1roundCt: treept: val: Integer):
(Ground the character tree With NIL's)
BEGIN
WITH t-, DO
B£GIN left:= NIL:
ENO (GROUND):
sum := val END
PROCEDURE 1et_2_minsCVAR posl, pos2: inte1er: VAR trl, tr2:
boolean):
(Find the two Characters or character trees with the smallest
frequpncles.)
VAR
count. mini, mln2: integer:
BEGIN tGET_2_MINS}
mint := ~axlnt; mln2:= maxlnt;
faR count := MinChar TO 127 00
WITH tallvlcountJ DO
If' Nor marlced
THEN
If' num_of < min2
THEN
IF num_of < minl
THEN
BEGIN
min2 := mint:
pos2 := posl:
trl := falSe;
END
ELSE
BEGIN
pos2 := count:
11I1n2 := num_of
END:
TO trees. t_num on
trs [count] ., DO
dn2
FOR count : = 1
WITH trees.
If' sum <
rH I!: Pi
If' NOT trl
IF NOT tr2
IF su'" < mini
THEN
BEGlPi
mi02 := m1nl:
post := count,
I!: NO
I!:LSE
BEGIN
END tGEr_2_~INSJ:
tr2 :
DOSl
mini
trl:
= c01Jnt:
= num_of
tr2 := false:
tr2 := trl:
trl := true,
pos2 := posl:
mini := sum
mln2 := sum: 00s2 : =
e:r~D;
THEN
THEN
tally[posl]. marKed := truel
tally[pos2]. marked := true
count
en
rn
"'tl
.....
rn
3
t:C
rn
::0
.....