1 /* Copyright (C) 1995, 1996, 1997, 1998, 1999 Aladdin Enterprises. All rights reserved.
2
3 This software is provided AS-IS with no warranty, either express or
4 implied.
5
6 This software is distributed under license and may not be copied,
7 modified or distributed except as expressly authorized under the terms
8 of the license contained in the file LICENSE in this distribution.
9
10 For more information about licensing, please refer to
11 http://www.ghostscript.com/licensing/. For information on
12 commercial licensing, go to http://www.artifex.com/licensing/ or
13 contact Artifex Software, Inc., 101 Lucas Valley Road #110,
14 San Rafael, CA 94903, U.S.A., +1(415)492-9861.
15 */
16
17 /* $Id: gsbittab.c,v 1.5 2002/06/16 05:48:55 lpd Exp $ */
18 /* Tables for bit operations */
19 #include "stdpre.h"
20 #include "gsbittab.h"
21
22 /* ---------------- Byte processing tables ---------------- */
23
24 /*
25 * byte_reverse_bits[B] = the byte B with the order of bits reversed.
26 */
27 const byte byte_reverse_bits[256] = {
28 bit_table_8(0, 1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80)
29 };
30
31 /*
32 * byte_right_mask[N] = a byte with N trailing 1s, 0 <= N <= 8.
33 */
34 const byte byte_right_mask[9] = {
35 0, 1, 3, 7, 0xf, 0x1f, 0x3f, 0x7f, 0xff
36 };
37
38 /*
39 * byte_count_bits[B] = the number of 1-bits in a byte with value B.
40 */
41 const byte byte_count_bits[256] = {
42 bit_table_8(0, 1, 1, 1, 1, 1, 1, 1, 1)
43 };
44
45 /* ---------------- Scanning tables ---------------- */
46
47 /*
48 * byte_bit_run_length_N[B], for 0 <= N <= 7, gives the length of the
49 * run of 1-bits starting at bit N in a byte with value B,
50 * numbering the bits in the byte as 01234567. If the run includes
51 * the low-order bit (i.e., might be continued into a following byte),
52 * the run length is increased by 8.
53 */
54
55 #define t8(n) n,n,n,n,n+1,n+1,n+2,n+11
56 #define r8(n) n,n,n,n,n,n,n,n
57 #define r16(n) r8(n),r8(n)
58 #define r32(n) r16(n),r16(n)
59 #define r64(n) r32(n),r32(n)
60 #define r128(n) r64(n),r64(n)
61 const byte byte_bit_run_length_0[256] = {
62 r128(0), r64(1), r32(2), r16(3), r8(4), t8(5)
63 };
64 const byte byte_bit_run_length_1[256] = {
65 r64(0), r32(1), r16(2), r8(3), t8(4),
66 r64(0), r32(1), r16(2), r8(3), t8(4)
67 };
68 const byte byte_bit_run_length_2[256] = {
69 r32(0), r16(1), r8(2), t8(3),
70 r32(0), r16(1), r8(2), t8(3),
71 r32(0), r16(1), r8(2), t8(3),
72 r32(0), r16(1), r8(2), t8(3)
73 };
74 const byte byte_bit_run_length_3[256] = {
75 r16(0), r8(1), t8(2), r16(0), r8(1), t8(2),
76 r16(0), r8(1), t8(2), r16(0), r8(1), t8(2),
77 r16(0), r8(1), t8(2), r16(0), r8(1), t8(2),
78 r16(0), r8(1), t8(2), r16(0), r8(1), t8(2)
79 };
80 const byte byte_bit_run_length_4[256] = {
81 r8(0), t8(1), r8(0), t8(1), r8(0), t8(1), r8(0), t8(1),
82 r8(0), t8(1), r8(0), t8(1), r8(0), t8(1), r8(0), t8(1),
83 r8(0), t8(1), r8(0), t8(1), r8(0), t8(1), r8(0), t8(1),
84 r8(0), t8(1), r8(0), t8(1), r8(0), t8(1), r8(0), t8(1),
85 };
86
87 #define rr8(a,b,c,d,e,f,g,h)\
88 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
89 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
90 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
91 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
92 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
93 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
94 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h,\
95 a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h, a,b,c,d,e,f,g,h
96 const byte byte_bit_run_length_5[256] = {
97 rr8(0, 0, 0, 0, 1, 1, 2, 11)
98 };
99 const byte byte_bit_run_length_6[256] = {
100 rr8(0, 0, 1, 10, 0, 0, 1, 10)
101 };
102 const byte byte_bit_run_length_7[256] = {
103 rr8(0, 9, 0, 9, 0, 9, 0, 9)
104 };
105
106 /* Pointer tables indexed by bit number. */
107
108 const byte *const byte_bit_run_length[8] = {
109 byte_bit_run_length_0, byte_bit_run_length_1,
110 byte_bit_run_length_2, byte_bit_run_length_3,
111 byte_bit_run_length_4, byte_bit_run_length_5,
112 byte_bit_run_length_6, byte_bit_run_length_7
113 };
114 const byte *const byte_bit_run_length_neg[8] = {
115 byte_bit_run_length_0, byte_bit_run_length_7,
116 byte_bit_run_length_6, byte_bit_run_length_5,
117 byte_bit_run_length_4, byte_bit_run_length_3,
118 byte_bit_run_length_2, byte_bit_run_length_1
119 };
120
121 /*
122 * byte_acegbdfh_to_abcdefgh[acegbdfh] = abcdefgh, where the letters
123 * denote the individual bits of the byte.
124 */
125 const byte byte_acegbdfh_to_abcdefgh[256] = {
126 bit_table_8(0, 0x80, 0x20, 0x08, 0x02, 0x40, 0x10, 0x04, 0x01)
127 };
128
129 /* Some C compilers insist on having executable code in every file.... */
130 void gsbittab_dummy(void); /* for picky compilers */
131 void
gsbittab_dummy(void)132 gsbittab_dummy(void)
133 {
134 }
135