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1.1 root 1: /*
2: * $Source: /u1/X/libis/RCS/misc.c,v $
3: * $Header: misc.c,v 1.1 86/11/17 14:34:18 swick Rel $
4: */
5:
6: #ifndef lint
7: static char *rcsid_misc_c = "$Header: misc.c,v 1.1 86/11/17 14:34:18 swick Rel $";
8: #endif lint
9:
10: #include "is-copyright.h"
11:
12: /*
13: * misc.c miscellaneous utility functions
14: *
15: * SwapShorts swap order of bytes in shorts
16: * SwapBits swap order of bits in bytes
17: * Overlap determine if two rectangles overlap
18: * Intersection return the intersection of two rectangles
19: *
20: * Copyright (c) 1986, Integrated Solutions, Inc.
21: */
22:
23: #include "Xis.h"
24:
25: #define MIN(a,b) (((a)<(b))?(a):(b))
26: #define MAX(a,b) (((a)>(b))?(a):(b))
27:
28: /*
29: * bit reverse array used by bit swapping routines
30: */
31: static unsigned char bitrev[] = {
32: 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
33: 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
34: 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
35: 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
36: 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
37: 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
38: 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
39: 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
40: 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
41: 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
42: 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
43: 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
44: 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
45: 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
46: 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
47: 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
48: 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
49: 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
50: 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
51: 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
52: 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
53: 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
54: 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
55: 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
56: 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
57: 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
58: 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
59: 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
60: 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
61: 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
62: 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
63: 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
64: };
65:
66: SwapShorts(wordp, bytecnt)
67: short *wordp;
68: int bytecnt;
69: {
70: register unsigned char *p = (unsigned char *)wordp;
71: register int cnt = bytecnt >> 1;
72: while (cnt--) {
73: register unsigned char tmp = *p;
74: *p = *(p+1);
75: *(p+1) = tmp;
76: p += sizeof(short);
77: }
78: }
79:
80: /*
81: * SwapBits - slow 'C' version
82: *
83: * swap bit 0 and bit 15, swap bit 1 and bit 14, etc.
84: */
85: SwapBits(wordp, bytecnt)
86: register short *wordp;
87: int bytecnt;
88: {
89: register int cnt = bytecnt >> 1;
90: while (cnt--) {
91: *wordp = (bitrev[(unsigned char)((*wordp)>>8)]<<8) |
92: (bitrev[(unsigned char)*wordp]);
93: wordp++;
94: }
95: }
96:
97: /*
98: * Overlap
99: */
100: int
101: Overlap(r1, r2)
102: CLIP r1, r2;
103: {
104: /* normalize rectangles */
105: if (r1.width < 0) {
106: r1.width = -r1.width;
107: r1.left -= r1.width-1;
108: }
109: if (r1.height < 0) {
110: r1.height = -r1.height;
111: r1.top -= r1.height-1;
112: }
113: if (r2.width < 0) {
114: r2.width = -r2.width;
115: r2.left -= r2.width-1;
116: }
117: if (r2.height < 0) {
118: r2.height = -r2.height;
119: r2.top -= r2.height-1;
120: }
121: if (r1.left < r2.left) {
122: if (r2.left >= r1.left + r1.width)
123: return (FALSE);
124: } else if (r1.left >= r2.left + r2.width) {
125: return (FALSE);
126: }
127:
128: if (r1.top < r2.top) {
129: if (r2.top >= r1.top + r1.height)
130: return (FALSE);
131: } else if (r1.top >= r2.top + r2.height) {
132: return (FALSE);
133: }
134:
135: return (TRUE);
136: }
137:
138: /*
139: * Intersection
140: */
141: CLIP
142: Intersection(r1, r2)
143: CLIP r1, r2;
144: {
145: CLIP i;
146:
147: /* normalize rectangles */
148: if (r1.width < 0) {
149: r1.width = -r1.width;
150: r1.left -= r1.width-1;
151: }
152: if (r1.height < 0) {
153: r1.height = -r1.height;
154: r1.top -= r1.height-1;
155: }
156: if (r2.width < 0) {
157: r2.width = -r2.width;
158: r2.left -= r2.width-1;
159: }
160: if (r2.height < 0) {
161: r2.height = -r2.height;
162: r2.top -= r2.height-1;
163: }
164: i.left = MAX(r1.left, r2.left);
165: i.top = MAX(r1.top, r2.top);
166: i.width = MIN(r1.left+r1.width, r2.left+r2.width) - i.left;
167: i.height = MIN(r1.top+r1.height, r2.top+r2.height) - i.top;
168:
169: return (i);
170: }
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