basen() now takes uint32_t rather than unsigned long, since that's

what it actually assumes.

New function nesab() is the reverse of basen().

diff --git a/lib/basen.c b/lib/basen.c
index 87d2795340d28657fd53616e86aff57d30009c99..7c1f9ec5c3ad72c4a0a81004b5a6e287b4ddf72a 100644 (file)
--- a/lib/basen.c
+++ b/lib/basen.c
@@ -31,7 +31,7 @@
  * @param nwords Length of bignum
  * @return !v
  */
  * @param nwords Length of bignum
  * @return !v
  */

-static int zero(const unsigned long *v, int nwords) {
+static int zero(const uint32_t *v, int nwords) {

   int n;
 
   for(n = 0; n < nwords && !v[n]; ++n)
   int n;
 
   for(n = 0; n < nwords && !v[n]; ++n)


@@ -47,7 +47,7 @@ static int zero(const unsigned long *v, int nwords) {
  *
  * The quotient is stored in @p v.
  */
  *
  * The quotient is stored in @p v.
  */

-static unsigned divide(unsigned long *v, int nwords, unsigned long m) {
+static unsigned divide(uint32_t *v, int nwords, unsigned long m) {

   unsigned long r = 0, a, b;
   int n;
 
   unsigned long r = 0, a, b;
   int n;
 


@@ -66,6 +66,31 @@ static unsigned divide(unsigned long *v, int nwords, unsigned long m) {
   return r;
 }
 
   return r;
 }
 

+/** @brief Multiple v by m and add a
+ * @param v Pointer to bigendian bignum
+ * @param nwords Length of bignum
+ * @param m Value to multiply by
+ * @param a Value to add
+ * @return 0 on success, non-0 on overflow
+ *
+ * Does v = m * v + a.
+ */
+static int mla(uint32_t *v, int nwords, uint32_t m, uint32_t a) {
+  int n = nwords - 1;
+  uint32_t carry = a;
+
+  while(n >= 0) {
+    const uint64_t p = (uint64_t)v[n] * m + carry;
+    carry = (uint32_t)(p >> 32);
+    v[n] = (uint32_t)p;
+    --n;
+  }
+  /* If there is still a carry then we overflowed */
+  return !!carry;
+}
+
+static const char basen_chars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+

 /** @brief Convert v to a chosen base
  * @param v Pointer to bigendian bignum (modified!)
  * @param nwords Length of bignum
 /** @brief Convert v to a chosen base
  * @param v Pointer to bigendian bignum (modified!)
  * @param nwords Length of bignum


@@ -75,26 +100,53 @@ static unsigned divide(unsigned long *v, int nwords, unsigned long m) {
  * @return 0 on success, -1 if the buffer is too small
  *
  * Converts @p v to a string in the given base using decimal digits, lower case
  * @return 0 on success, -1 if the buffer is too small
  *
  * Converts @p v to a string in the given base using decimal digits, lower case

- * letter sand upper case letters as digits.
+ * letters and upper case letters as digits.
+ *
+ * The inverse of nesab().

  */
  */

-int basen(unsigned long *v,
+int basen(uint32_t *v,

          int nwords,
          char buffer[],
          size_t bufsize,
          unsigned base) {
   size_t i = bufsize;
          int nwords,
          char buffer[],
          size_t bufsize,
          unsigned base) {
   size_t i = bufsize;

-  static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

   
   do {
     if(i <= 1)
       return -1;                       /* overflow */
   
   do {
     if(i <= 1)
       return -1;                       /* overflow */

-    buffer[--i] = chars[divide(v, nwords, base)];
+    buffer[--i] = basen_chars[divide(v, nwords, base)];

   } while(!zero(v, nwords));
   memmove(buffer, buffer + i, bufsize - i);
   buffer[bufsize - i] = 0;
   return 0;
 }
 
   } while(!zero(v, nwords));
   memmove(buffer, buffer + i, bufsize - i);
   buffer[bufsize - i] = 0;
   return 0;
 }
 

+/** @brief Convert a string back to a large integer in an arbitrary base
+ * @param v Where to store result as a bigendian bignum
+ * @param nwords Space available in @p v
+ * @param s Input string
+ * @param base Number base (2..62)
+ * @return 0 on success, non-0 on overflow or invalid input
+ *
+ * The inverse of basen().  If the number is much smaller than the buffer then
+ * the first words will be 0.
+ */
+int nesab(uint32_t *v,
+          int nwords,
+          const char *s,
+          unsigned base) {
+  /* Initialize to 0 */
+  memset(v, 0, nwords * sizeof *v);
+  while(*s) {
+    const char *dp = strchr(basen_chars, *s++);
+    if(!dp)
+      return -1;
+    if(mla(v, nwords, base, dp - basen_chars))
+      return -1;
+  }
+  return 0;
+}
+

 /*
 Local Variables:
 c-basic-offset:2
 /*
 Local Variables:
 c-basic-offset:2

diff --git a/lib/basen.h b/lib/basen.h
index 717f2eaeb48396fa887dc3b3883d9aeb9ceef2a1..c1a60f0c7835c728b649d0a95048e6186c0057e7 100644 (file)
--- a/lib/basen.h
+++ b/lib/basen.h
@@ -19,7 +19,7 @@
 #ifndef BASEN_H
 #define BASEN_H
 
 #ifndef BASEN_H
 #define BASEN_H
 

-int basen(unsigned long *v,
+int basen(uint32_t *v,

          int nwords,
          char buffer[],
          size_t bufsize,
          int nwords,
          char buffer[],
          size_t bufsize,


@@ -29,6 +29,11 @@ int basen(unsigned long *v,
  * Returns 0 on success or -1 on overflow.
  */
 
  * Returns 0 on success or -1 on overflow.
  */
 

+int nesab(uint32_t *v,
+          int nwords,
+          const char *s,
+          unsigned base);
+

 #endif /* BASEN_H */
 
 /*
 #endif /* BASEN_H */
 
 /*

diff --git a/lib/random.c b/lib/random.c
index 3f8f714a8829f9ad969a00d51de3b4de457667d4..d6be3d9f47ec27614f8a536f8a5c88a104b9b63a 100644 (file)
--- a/lib/random.c
+++ b/lib/random.c
@@ -75,7 +75,7 @@ void random_get(void *ptr, size_t bytes) {
 
 /** @brief Return a random ID string */
 char *random_id(void) {
 
 /** @brief Return a random ID string */
 char *random_id(void) {

-  unsigned long words[2];
+  uint32_t words[2];

   char id[128];
 
   random_get(words, sizeof words);
   char id[128];
 
   random_get(words, sizeof words);

diff --git a/libtests/t-basen.c b/libtests/t-basen.c
index 715490ca9e976d9d85b1797ccef925185ed20aea..3cbc044a27ea7120f9d3f5edcc8f8a363729eb05 100644 (file)
--- a/libtests/t-basen.c
+++ b/libtests/t-basen.c
@@ -18,12 +18,22 @@
 #include "test.h"
 
 static void test_basen(void) {
 #include "test.h"
 
 static void test_basen(void) {

-  unsigned long v[64];
+  uint32_t v[64];

   char buffer[1024];
 
   v[0] = 999;
   insist(basen(v, 1, buffer, sizeof buffer, 10) == 0);
   check_string(buffer, "999");
   char buffer[1024];
 
   v[0] = 999;
   insist(basen(v, 1, buffer, sizeof buffer, 10) == 0);
   check_string(buffer, "999");

+  memset(v, 0xFF, sizeof v);
+  insist(nesab(v, 1, buffer, 10) == 0);
+  check_integer(v[0], 999);
+  check_integer(v[1], 0xFFFFFFFF);
+  insist(nesab(v, 4, buffer, 10) == 0);
+  check_integer(v[0], 0);
+  check_integer(v[1], 0);
+  check_integer(v[2], 0);
+  check_integer(v[3], 999);
+  check_integer(v[4], 0xFFFFFFFF);

 
   v[0] = 1+2*7+3*7*7+4*7*7*7;
   insist(basen(v, 1, buffer, sizeof buffer, 7) == 0);
 
   v[0] = 1+2*7+3*7*7+4*7*7*7;
   insist(basen(v, 1, buffer, sizeof buffer, 7) == 0);


@@ -35,6 +45,24 @@ static void test_basen(void) {
   v[3] = 0x0C0D0E0F;
   insist(basen(v, 4, buffer, sizeof buffer, 256) == 0);
   check_string(buffer, "123456789abcdef");
   v[3] = 0x0C0D0E0F;
   insist(basen(v, 4, buffer, sizeof buffer, 256) == 0);
   check_string(buffer, "123456789abcdef");

+  memset(v, 0xFF, sizeof v);
+  insist(nesab(v, 4, buffer, 256) == 0);
+  check_integer(v[0], 0x00010203);
+  check_integer(v[1], 0x04050607);
+  check_integer(v[2], 0x08090A0B);
+  check_integer(v[3], 0x0C0D0E0F);
+  check_integer(v[4], 0xFFFFFFFF);
+  memset(v, 0xFF, sizeof v);
+  insist(nesab(v, 8, buffer, 256) == 0);
+  check_integer(v[0], 0);
+  check_integer(v[1], 0);
+  check_integer(v[2], 0);
+  check_integer(v[3], 0);
+  check_integer(v[4], 0x00010203);
+  check_integer(v[5], 0x04050607);
+  check_integer(v[6], 0x08090A0B);
+  check_integer(v[7], 0x0C0D0E0F);
+  check_integer(v[8], 0xFFFFFFFF);

 
   v[0] = 0x00010203;
   v[1] = 0x04050607;
 
   v[0] = 0x00010203;
   v[1] = 0x04050607;


@@ -42,6 +70,24 @@ static void test_basen(void) {
   v[3] = 0x0C0D0E0F;
   insist(basen(v, 4, buffer, sizeof buffer, 16) == 0);
   check_string(buffer, "102030405060708090a0b0c0d0e0f");
   v[3] = 0x0C0D0E0F;
   insist(basen(v, 4, buffer, sizeof buffer, 16) == 0);
   check_string(buffer, "102030405060708090a0b0c0d0e0f");

+  memset(v, 0xFF, sizeof v);
+  insist(nesab(v, 4, buffer, 16) == 0);
+  check_integer(v[0], 0x00010203);
+  check_integer(v[1], 0x04050607);
+  check_integer(v[2], 0x08090A0B);
+  check_integer(v[3], 0x0C0D0E0F);
+  check_integer(v[4], 0xFFFFFFFF);
+  memset(v, 0xFF, sizeof v);
+  insist(nesab(v, 8, buffer, 16) == 0);
+  check_integer(v[0], 0);
+  check_integer(v[1], 0);
+  check_integer(v[2], 0);
+  check_integer(v[3], 0);
+  check_integer(v[4], 0x00010203);
+  check_integer(v[5], 0x04050607);
+  check_integer(v[6], 0x08090A0B);
+  check_integer(v[7], 0x0C0D0E0F);
+  check_integer(v[8], 0xFFFFFFFF);

 
   v[0] = 0x00010203;
   v[1] = 0x04050607;
 
   v[0] = 0x00010203;
   v[1] = 0x04050607;