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1 /* Packed decimal conversion module for the decNumber C Library.
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2 Copyright (C) 2007, 2009 Free Software Foundation, Inc.
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3 Contributed by IBM Corporation. Author Mike Cowlishaw.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify it under
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8 the terms of the GNU General Public License as published by the Free
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9 Software Foundation; either version 3, or (at your option) any later
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10 version.
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11
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12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 Under Section 7 of GPL version 3, you are granted additional
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18 permissions described in the GCC Runtime Library Exception, version
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19 3.1, as published by the Free Software Foundation.
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20
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21 You should have received a copy of the GNU General Public License and
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22 a copy of the GCC Runtime Library Exception along with this program;
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23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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24 <http://www.gnu.org/licenses/>. */
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25
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26 /* ------------------------------------------------------------------ */
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27 /* Packed Decimal conversion module */
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28 /* ------------------------------------------------------------------ */
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29 /* This module comprises the routines for Packed Decimal format */
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30 /* numbers. Conversions are supplied to and from decNumber, which in */
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31 /* turn supports: */
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32 /* conversions to and from string */
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33 /* arithmetic routines */
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34 /* utilities. */
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35 /* Conversions from decNumber to and from densely packed decimal */
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36 /* formats are provided by the decimal32 through decimal128 modules. */
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37 /* ------------------------------------------------------------------ */
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38
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39 #include <string.h> /* for NULL */
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40 #include "decNumber.h" /* base number library */
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41 #include "decPacked.h" /* packed decimal */
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42 #include "decNumberLocal.h" /* decNumber local types, etc. */
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43
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44 /* ------------------------------------------------------------------ */
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45 /* decPackedFromNumber -- convert decNumber to BCD Packed Decimal */
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46 /* */
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47 /* bcd is the BCD bytes */
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48 /* length is the length of the BCD array */
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49 /* scale is the scale result */
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50 /* dn is the decNumber */
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51 /* returns bcd, or NULL if error */
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52 /* */
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53 /* The number is converted to a BCD packed decimal byte array, */
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54 /* right aligned in the bcd array, whose length is indicated by the */
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55 /* second parameter. The final 4-bit nibble in the array will be a */
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56 /* sign nibble, C (1100) for + and D (1101) for -. Unused bytes and */
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57 /* nibbles to the left of the number are set to 0. */
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58 /* */
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59 /* scale is set to the scale of the number (this is the exponent, */
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60 /* negated). To force the number to a specified scale, first use the */
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61 /* decNumberRescale routine, which will round and change the exponent */
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62 /* as necessary. */
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63 /* */
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64 /* If there is an error (that is, the decNumber has too many digits */
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65 /* to fit in length bytes, or it is a NaN or Infinity), NULL is */
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66 /* returned and the bcd and scale results are unchanged. Otherwise */
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67 /* bcd is returned. */
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68 /* ------------------------------------------------------------------ */
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69 uByte * decPackedFromNumber(uByte *bcd, Int length, Int *scale,
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70 const decNumber *dn) {
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71 const Unit *up=dn->lsu; /* Unit array pointer */
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72 uByte obyte, *out; /* current output byte, and where it goes */
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73 Int indigs=dn->digits; /* digits processed */
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74 uInt cut=DECDPUN; /* downcounter per Unit */
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75 uInt u=*up; /* work */
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76 uInt nib; /* .. */
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77 #if DECDPUN<=4
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78 uInt temp; /* .. */
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79 #endif
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80
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81 if (dn->digits>length*2-1 /* too long .. */
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82 ||(dn->bits & DECSPECIAL)) return NULL; /* .. or special -- hopeless */
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83
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84 if (dn->bits&DECNEG) obyte=DECPMINUS; /* set the sign .. */
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85 else obyte=DECPPLUS;
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86 *scale=-dn->exponent; /* .. and scale */
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87
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88 /* loop from lowest (rightmost) byte */
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89 out=bcd+length-1; /* -> final byte */
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90 for (; out>=bcd; out--) {
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91 if (indigs>0) {
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92 if (cut==0) {
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93 up++;
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94 u=*up;
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95 cut=DECDPUN;
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96 }
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97 #if DECDPUN<=4
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98 temp=(u*6554)>>16; /* fast /10 */
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99 nib=u-X10(temp);
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100 u=temp;
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101 #else
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102 nib=u%10; /* cannot use *6554 trick :-( */
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103 u=u/10;
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104 #endif
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105 obyte|=(nib<<4);
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106 indigs--;
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107 cut--;
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108 }
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109 *out=obyte;
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110 obyte=0; /* assume 0 */
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111 if (indigs>0) {
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112 if (cut==0) {
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113 up++;
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114 u=*up;
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115 cut=DECDPUN;
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116 }
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117 #if DECDPUN<=4
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118 temp=(u*6554)>>16; /* as above */
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119 obyte=(uByte)(u-X10(temp));
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120 u=temp;
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121 #else
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122 obyte=(uByte)(u%10);
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123 u=u/10;
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124 #endif
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125 indigs--;
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126 cut--;
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127 }
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128 } /* loop */
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129
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130 return bcd;
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131 } /* decPackedFromNumber */
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132
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133 /* ------------------------------------------------------------------ */
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134 /* decPackedToNumber -- convert BCD Packed Decimal to a decNumber */
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135 /* */
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136 /* bcd is the BCD bytes */
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137 /* length is the length of the BCD array */
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138 /* scale is the scale associated with the BCD integer */
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139 /* dn is the decNumber [with space for length*2 digits] */
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140 /* returns dn, or NULL if error */
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141 /* */
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142 /* The BCD packed decimal byte array, together with an associated */
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143 /* scale, is converted to a decNumber. The BCD array is assumed full */
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144 /* of digits, and must be ended by a 4-bit sign nibble in the least */
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145 /* significant four bits of the final byte. */
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146 /* */
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147 /* The scale is used (negated) as the exponent of the decNumber. */
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148 /* Note that zeros may have a sign and/or a scale. */
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149 /* */
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150 /* The decNumber structure is assumed to have sufficient space to */
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151 /* hold the converted number (that is, up to length*2-1 digits), so */
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152 /* no error is possible unless the adjusted exponent is out of range, */
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153 /* no sign nibble was found, or a sign nibble was found before the */
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154 /* final nibble. In these error cases, NULL is returned and the */
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155 /* decNumber will be 0. */
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156 /* ------------------------------------------------------------------ */
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157 decNumber * decPackedToNumber(const uByte *bcd, Int length,
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158 const Int *scale, decNumber *dn) {
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159 const uByte *last=bcd+length-1; /* -> last byte */
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160 const uByte *first; /* -> first non-zero byte */
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161 uInt nib; /* work nibble */
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162 Unit *up=dn->lsu; /* output pointer */
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163 Int digits; /* digits count */
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164 Int cut=0; /* phase of output */
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165
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166 decNumberZero(dn); /* default result */
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167 last=&bcd[length-1];
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168 nib=*last & 0x0f; /* get the sign */
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169 if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG;
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170 else if (nib<=9) return NULL; /* not a sign nibble */
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171
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172 /* skip leading zero bytes [final byte is always non-zero, due to sign] */
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173 for (first=bcd; *first==0;) first++;
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174 digits=(last-first)*2+1; /* calculate digits .. */
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175 if ((*first & 0xf0)==0) digits--; /* adjust for leading zero nibble */
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176 if (digits!=0) dn->digits=digits; /* count of actual digits [if 0, */
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177 /* leave as 1] */
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178
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179 /* check the adjusted exponent; note that scale could be unbounded */
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180 dn->exponent=-*scale; /* set the exponent */
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181 if (*scale>=0) { /* usual case */
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182 if ((dn->digits-*scale-1)<-DECNUMMAXE) { /* underflow */
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183 decNumberZero(dn);
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184 return NULL;}
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185 }
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186 else { /* -ve scale; +ve exponent */
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187 /* need to be careful to avoid wrap, here, also BADINT case */
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188 if ((*scale<-DECNUMMAXE) /* overflow even without digits */
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189 || ((dn->digits-*scale-1)>DECNUMMAXE)) { /* overflow */
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190 decNumberZero(dn);
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191 return NULL;}
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192 }
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193 if (digits==0) return dn; /* result was zero */
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194
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195 /* copy the digits to the number's units, starting at the lsu */
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196 /* [unrolled] */
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197 for (;;) { /* forever */
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198 /* left nibble first */
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199 nib=(unsigned)(*last & 0xf0)>>4;
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200 /* got a digit, in nib */
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201 if (nib>9) {decNumberZero(dn); return NULL;}
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202
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203 if (cut==0) *up=(Unit)nib;
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204 else *up=(Unit)(*up+nib*DECPOWERS[cut]);
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205 digits--;
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206 if (digits==0) break; /* got them all */
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207 cut++;
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208 if (cut==DECDPUN) {
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209 up++;
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210 cut=0;
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211 }
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212 last--; /* ready for next */
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213 nib=*last & 0x0f; /* get right nibble */
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214 if (nib>9) {decNumberZero(dn); return NULL;}
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215
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216 /* got a digit, in nib */
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217 if (cut==0) *up=(Unit)nib;
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218 else *up=(Unit)(*up+nib*DECPOWERS[cut]);
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219 digits--;
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220 if (digits==0) break; /* got them all */
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221 cut++;
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222 if (cut==DECDPUN) {
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223 up++;
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224 cut=0;
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225 }
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226 } /* forever */
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227
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228 return dn;
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229 } /* decPackedToNumber */
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230
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