[f40a309] | 1 | /*
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| 2 | =============================================================================
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| 3 | dec2fr.c -- Buchla 700 fractional 2's complement conversion functions
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| 4 | Version 10 -- 1987-12-06 -- D.N. Lynx Crowe
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| 5 | =============================================================================
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| 6 | */
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| 7 |
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| 8 | #define TESTER 0
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| 9 |
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| 10 | #include "stddefs.h"
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[e225e77] | 11 | #include "stdio.h"
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[f40a309] | 12 |
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| 13 | #define SFACT 1000L /* scale factor */
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| 14 |
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[7258c6a] | 15 | static int32_t d2f[][10] = { /* decimal to fraction table */
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[f40a309] | 16 |
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| 17 | {0x00000000L, 0x000019A0L, 0x00003336L, 0x00004CD0L, 0x00006668L,
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| 18 | 0x00008000L, 0x000099A0L, 0x0000B336L, 0x0000CCCEL, 0x0000E668L},
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| 19 |
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| 20 | {0x00000000L, 0x00000290L, 0x00000520L, 0x000007B0L, 0x00000A40L,
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| 21 | 0x00000CD0L, 0x00000F60L, 0x000011F0L, 0x00001480L, 0x00001710L}
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| 22 | };
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| 23 |
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[7258c6a] | 24 | static int32_t f2d[] = { /* fraction to decimal table */
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[f40a309] | 25 |
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| 26 | 50000L, 25000L, 12500L, 6250L,
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| 27 | 3125L, 1562L, 781L, 390L,
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| 28 | 195L, 97L, 48L, 24L,
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| 29 | 12L, 6L, 3L, 1L
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| 30 | };
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| 31 |
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| 32 | /* |
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| 33 |
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| 34 | */
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| 35 |
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| 36 | /*
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| 37 | =============================================================================
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| 38 | dec2fr() -- convert an ASCII decimal string to fractional binary
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| 39 |
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| 40 | The input string is 4 characters in the range 100- to 100+ inclusive.
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| 41 | The result is a 2's complement binary fractional value.
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| 42 | =============================================================================
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| 43 | */
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[7258c6a] | 44 |
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[f40a309] | 45 | int16_t dec2fr(int8_t *s)
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[7258c6a] | 46 | {
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[f40a309] | 47 | register int16_t i;
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| 48 |
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| 49 | if (s[0] EQ '1') {
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| 50 |
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| 51 | if (s[1] EQ '0') {
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| 52 |
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| 53 | if (s[2] EQ '0') {
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| 54 |
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| 55 | if (s[3] EQ '-')
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| 56 | return(0x8000); /* -100 */
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| 57 | else
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| 58 | return(0x7FFF); /* +100 */
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| 59 |
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| 60 | } else {
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| 61 |
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| 62 | return(0xFFFF); /* ERROR */
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| 63 | }
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| 64 |
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| 65 | } else {
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| 66 |
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| 67 | return(0xFFFF); /* ERROR */
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| 68 |
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| 69 | }
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| 70 |
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| 71 | /* |
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| 72 |
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| 73 | */
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| 74 |
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| 75 | } else if (s[0] EQ '0') {
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| 76 |
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| 77 | i = (d2f[0][s[1] - '0'] + d2f[1][s[2] - '0']) >> 1;
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| 78 |
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[9519422] | 79 | if (s[3] EQ '-') {
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[f40a309] | 80 |
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| 81 | if (i)
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| 82 | return(~i); /* negative number */
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| 83 | else
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| 84 | return(0); /* zero is always 0 */
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| 85 |
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| 86 | } else {
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| 87 |
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| 88 | return(i); /* positive number */
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| 89 | }
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| 90 | }
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| 91 |
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| 92 | return(0xFFFF); /* ERROR */
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| 93 | }
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| 94 |
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| 95 | /* |
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| 96 |
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| 97 | */
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| 98 |
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| 99 | /*
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| 100 | =============================================================================
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| 101 | fr2dec() -- convert a 2's complement fraction to decimal ASCII notation
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| 102 |
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| 103 | The input is a 2's complement binary fractional value.
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| 104 | The result string is 4 characters in the range 100- to 100+ inclusive.
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[7258c6a] | 105 | =============================================================================
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[f40a309] | 106 | */
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[7258c6a] | 107 |
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| 108 | int8_t *fr2dec(int16_t v, int8_t *s)
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[f40a309] | 109 | {
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| 110 | register int32_t acc, sc;
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| 111 | register int16_t i, p;
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| 112 |
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| 113 | if (v EQ 0x7FFF) { /* +100 */
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| 114 |
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| 115 | sprintf(s, "100+");
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| 116 | return(s);
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| 117 | }
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| 118 |
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| 119 | if (v EQ 0x8000) { /* -100 */
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| 120 |
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| 121 | sprintf(s, "100-");
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| 122 | return(s);
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| 123 | }
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| 124 |
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| 125 | if (v & 0x8000) {
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| 126 |
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| 127 | v = ~v; /* negative number */
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| 128 | p = '-';
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| 129 |
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| 130 | } else {
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| 131 |
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| 132 | p = '+'; /* positive number */
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| 133 | }
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| 134 |
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| 135 | acc = 0;
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| 136 |
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| 137 | for (i = 0; i LT 15; i++)
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| 138 | if (v & (1 << (14 - i)))
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| 139 | acc += f2d[i];
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[7258c6a] | 140 |
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[f40a309] | 141 | sc = SFACT;
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| 142 | acc /= sc;
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| 143 | sprintf(s, "%03d%c", (int16_t)acc, p);
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| 144 | return(s);
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| 145 | }
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| 146 |
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| 147 | /* |
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| 148 |
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| 149 | */
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| 150 |
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[e225e77] | 151 | #if TESTER
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| 152 |
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[f40a309] | 153 | #include "stdio.h"
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| 154 |
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| 155 | #include "stdio.h"
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| 156 |
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| 157 | extern int memcmp();
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| 158 |
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| 159 | char t[8], v[8];
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| 160 |
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| 161 | /*
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| 162 | =============================================================================
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| 163 | test program for fractional two's complement conversion functions
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| 164 | =============================================================================
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| 165 | */
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| 166 |
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| 167 | main()
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| 168 | {
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| 169 | register short i;
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| 170 | register short u;
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| 171 |
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| 172 | for (i = 0; i < 101; i++) {
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| 173 |
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| 174 | if (i EQ 50)
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| 175 | printf("\f");
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| 176 |
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| 177 | sprintf(t, "%03d+", i);
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| 178 | u = dec2fr(t);
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| 179 |
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| 180 | if (u EQ 0xFFFF) {
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| 181 |
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| 182 | printf("[%s] = ERROR = ?????? ", t);
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| 183 |
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| 184 | } else {
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| 185 |
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| 186 | fr2dec(u, v);
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| 187 | printf("[%s] = 0x%04x = [%s]", t, u, v);
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| 188 | }
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| 189 |
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| 190 | printf(" %s ", memcmp(t, v, 4) ? "<--" : " ");
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| 191 |
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| 192 | sprintf(t, "%03d-", i);
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| 193 | u = dec2fr(t);
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| 194 |
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| 195 | if (u EQ 0xFFFF) {
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| 196 |
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| 197 | printf(" [%s] = ERROR = ??????\n", t);
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| 198 |
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| 199 | } else {
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| 200 |
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| 201 | fr2dec(u, v);
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| 202 | printf(" [%s] = 0x%04x = [%s]", t, u, v);
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| 203 | }
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| 204 |
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| 205 | printf(" %s\n", memcmp(t, v, 4) ? "<--" : "");
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| 206 |
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| 207 | }
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| 208 | }
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| 209 |
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| 210 | #endif
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