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icu46/source/test/intltest/punyref.c

+/*
+ *******************************************************************************
+ *
+ *   Copyright (C) 2003-2005, International Business Machines
+ *   Corporation and others.  All Rights Reserved.
+ *
+ *******************************************************************************
+ *   file name:  punyref.h
+ *   encoding:   US-ASCII
+ *   tab size:   8 (not used)
+ *   indentation:4
+ *
+ *   created on: 2003feb1
+ *   created by: Ram Viswanadha
+ */
+
+/*
+Disclaimer and license
+
+    Regarding this entire document or any portion of it (including
+    the pseudocode and C code), the author makes no guarantees and
+    is not responsible for any damage resulting from its use.  The
+    author grants irrevocable permission to anyone to use, modify,
+    and distribute it in any way that does not diminish the rights
+    of anyone else to use, modify, and distribute it, provided that
+    redistributed derivative works do not contain misleading author or
+    version information.  Derivative works need not be licensed under
+    similar terms.
+
+punycode.c 0.4.0 (2001-Nov-17-Sat)
+http://www.cs.berkeley.edu/~amc/idn/
+Adam M. Costello
+http://www.nicemice.net/amc/
+*/
+
+/**********************************************************/
+/* Implementation (would normally go in its own .c file): */
+
+#include <string.h>
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_IDNA
+
+#include "punyref.h"
+
+/*** Bootstring parameters for Punycode ***/
+
+enum { base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700,
+       initial_bias = 72, initial_n = 0x80, delimiter = 0x2D };
+
+/* basic(cp) tests whether cp is a basic code point: */
+#define basic(cp) ((punycode_uint)(cp) < 0x80)
+
+/* delim(cp) tests whether cp is a delimiter: */
+#define delim(cp) ((cp) == delimiter)
+
+U_CDECL_BEGIN
+/* decode_digit(cp) returns the numeric value of a basic code */
+/* point (for use in representing integers) in the range 0 to */
+/* base-1, or base if cp is does not represent a value.       */
+
+static punycode_uint decode_digit(punycode_uint cp)
+{
+  return  cp - 48 < 10 ? cp - 22 :  cp - 65 < 26 ? cp - 65 :
+          cp - 97 < 26 ? cp - 97 :  base;
+}
+
+/* encode_digit(d,flag) returns the basic code point whose value      */
+/* (when used for representing integers) is d, which needs to be in   */
+/* the range 0 to base-1.  The lowercase form is used unless flag is  */
+/* nonzero, in which case the uppercase form is used.  The behavior   */
+/* is undefined if flag is nonzero and digit d has no uppercase form. */
+
+static char encode_digit(punycode_uint d, int flag)
+{
+  return (char) d + 22 + 75 * (d < 26) - ((flag != 0) << 5);
+  /*  0..25 map to ASCII a..z or A..Z */
+  /* 26..35 map to ASCII 0..9         */
+}
+
+/* flagged(bcp) tests whether a basic code point is flagged */
+/* (uppercase).  The behavior is undefined if bcp is not a  */
+/* basic code point.                                        */
+
+#define flagged(bcp) ((punycode_uint)(bcp) - 65 < 26)
+
+/* encode_basic(bcp,flag) forces a basic code point to lowercase */
+/* if flag is zero, uppercase if flag is nonzero, and returns    */
+/* the resulting code point.  The code point is unchanged if it  */
+/* is caseless.  The behavior is undefined if bcp is not a basic */
+/* code point.                                                   */
+
+static char encode_basic(punycode_uint bcp, int flag)
+{
+  bcp -= (bcp - 97 < 26) << 5;
+  return (char) bcp + ((!flag && (bcp - 65 < 26)) << 5);
+}
+
+/*** Platform-specific constants ***/
+
+/* maxint is the maximum value of a punycode_uint variable: */
+static const punycode_uint maxint = (punycode_uint) (-1);
+/* Because maxint is unsigned, -1 becomes the maximum value. */
+
+/*** Bias adaptation function ***/
+
+static punycode_uint adapt(
+  punycode_uint delta, punycode_uint numpoints, int firsttime )
+{
+  punycode_uint k;
+
+  delta = firsttime ? delta / damp : delta >> 1;
+  /* delta >> 1 is a faster way of doing delta / 2 */
+  delta += delta / numpoints;
+
+  for (k = 0;  delta > ((base - tmin) * tmax) / 2;  k += base) {
+    delta /= base - tmin;
+  }
+
+  return k + (base - tmin + 1) * delta / (delta + skew);
+}
+
+/*** Main encode function ***/
+
+enum punycode_status punycode_encode(
+  punycode_uint input_length,
+  const punycode_uint input[],
+  const unsigned char case_flags[],
+  punycode_uint *output_length,
+  char output[] )
+{
+  punycode_uint n, delta, h, b, out, max_out, bias, j, m, q, k, t;
+
+  /* Initialize the state: */
+
+  n = initial_n;
+  delta = out = 0;
+  max_out = *output_length;
+  bias = initial_bias;
+
+  /* Handle the basic code points: */
+
+  for (j = 0;  j < input_length;  ++j) {
+    if (basic(input[j])) {
+      if (max_out - out < 2) return punycode_big_output;
+      output[out++] = (char)
+        (case_flags ?  encode_basic(input[j], case_flags[j]) : input[j]);
+    }
+    /* else if (input[j] < n) return punycode_bad_input; */
+    /* (not needed for Punycode with unsigned code points) */
+  }
+
+  h = b = out;
+
+  /* h is the number of code points that have been handled, b is the  */
+  /* number of basic code points, and out is the number of characters */
+  /* that have been output.                                           */
+
+  if (b > 0) output[out++] = delimiter;
+
+  /* Main encoding loop: */
+
+  while (h < input_length) {
+    /* All non-basic code points < n have been     */
+    /* handled already.  Find the next larger one: */
+
+    for (m = maxint, j = 0;  j < input_length;  ++j) {
+      /* if (basic(input[j])) continue; */
+      /* (not needed for Punycode) */
+      if (input[j] >= n && input[j] < m) m = input[j];
+    }
+
+    /* Increase delta enough to advance the decoder's    */
+    /* <n,i> state to <m,0>, but guard against overflow: */
+
+    if (m - n > (maxint - delta) / (h + 1)) return punycode_overflow;
+    delta += (m - n) * (h + 1);
+    n = m;
+
+    for (j = 0;  j < input_length;  ++j) {
+      /* Punycode does not need to check whether input[j] is basic: */
+      if (input[j] < n /* || basic(input[j]) */ ) {
+        if (++delta == 0) return punycode_overflow;
+      }
+
+      if (input[j] == n) {
+        /* Represent delta as a generalized variable-length integer: */
+
+        for (q = delta, k = base;  ;  k += base) {
+          if (out >= max_out) return punycode_big_output;
+          t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
+              k >= bias + tmax ? tmax : k - bias;
+          if (q < t) break;
+          output[out++] = encode_digit(t + (q - t) % (base - t), 0);
+          q = (q - t) / (base - t);
+        }
+
+        output[out++] = encode_digit(q, case_flags && case_flags[j]);
+        bias = adapt(delta, h + 1, h == b);
+        delta = 0;
+        ++h;
+      }
+    }
+
+    ++delta, ++n;
+  }
+
+  *output_length = out;
+  return punycode_success;
+}
+
+/*** Main decode function ***/
+
+enum punycode_status punycode_decode(
+  punycode_uint input_length,
+  const char input[],
+  punycode_uint *output_length,
+  punycode_uint output[],
+  unsigned char case_flags[] )
+{
+  punycode_uint n, out, i, max_out, bias,
+                 b, j, in, oldi, w, k, digit, t;
+
+  /* Initialize the state: */
+
+  n = initial_n;
+  out = i = 0;
+  max_out = *output_length;
+  bias = initial_bias;
+
+  /* Handle the basic code points:  Let b be the number of input code */
+  /* points before the last delimiter, or 0 if there is none, then    */
+  /* copy the first b code points to the output.                      */
+
+  for (b = j = 0;  j < input_length;  ++j) if (delim(input[j])) b = j;
+  if (b > max_out) return punycode_big_output;
+
+  for (j = 0;  j < b;  ++j) {
+    if (case_flags) case_flags[out] = flagged(input[j]);
+    if (!basic(input[j])) return punycode_bad_input;
+    output[out++] = input[j];
+  }
+
+  /* Main decoding loop:  Start just after the last delimiter if any  */
+  /* basic code points were copied; start at the beginning otherwise. */
+
+  for (in = b > 0 ? b + 1 : 0;  in < input_length;  ++out) {
+
+    /* in is the index of the next character to be consumed, and */
+    /* out is the number of code points in the output array.     */
+
+    /* Decode a generalized variable-length integer into delta,  */
+    /* which gets added to i.  The overflow checking is easier   */
+    /* if we increase i as we go, then subtract off its starting */
+    /* value at the end to obtain delta.                         */
+
+    for (oldi = i, w = 1, k = base;  ;  k += base) {
+      if (in >= input_length) return punycode_bad_input;
+      digit = decode_digit(input[in++]);
+      if (digit >= base) return punycode_bad_input;
+      if (digit > (maxint - i) / w) return punycode_overflow;
+      i += digit * w;
+      t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
+          k >= bias + tmax ? tmax : k - bias;
+      if (digit < t) break;
+      if (w > maxint / (base - t)) return punycode_overflow;
+      w *= (base - t);
+    }
+
+    bias = adapt(i - oldi, out + 1, oldi == 0);
+
+    /* i was supposed to wrap around from out+1 to 0,   */
+    /* incrementing n each time, so we'll fix that now: */
+
+    if (i / (out + 1) > maxint - n) return punycode_overflow;
+    n += i / (out + 1);
+    i %= (out + 1);
+
+    /* Insert n at position i of the output: */
+
+    /* not needed for Punycode: */
+    /* if (decode_digit(n) <= base) return punycode_invalid_input; */
+    if (out >= max_out) return punycode_big_output;
+
+    if (case_flags) {
+      memmove(case_flags + i + 1, case_flags + i, out - i);
+      /* Case of last character determines uppercase flag: */
+      case_flags[i] = flagged(input[in - 1]);
+    }
+
+    memmove(output + i + 1, output + i, (out - i) * sizeof *output);
+    output[i++] = n;
+  }
+
+  *output_length = out;
+  return punycode_success;
+}
+
+U_CDECL_END
+
+#endif /* #if !UCONFIG_NO_IDNA */