Extract simple integer math into its own module

.gitignore

@@ -173,6 +173,8 @@ uptime-*.json
 /src/lib/libtor-ctime-testing.a
 /src/lib/libtor-err.a
 /src/lib/libtor-err-testing.a
+/src/lib/libtor-intmath.a
+/src/lib/libtor-intmath-testing.a
 /src/lib/libtor-malloc.a
 /src/lib/libtor-malloc-testing.a
 /src/lib/libtor-string.a

Makefile.am

@@ -45,6 +45,7 @@ TOR_UTIL_LIBS = \
 	src/lib/libtor-malloc.a \
         src/lib/libtor-wallclock.a \
         src/lib/libtor-err.a \
+        src/lib/libtor-intmath.a \
 	src/lib/libtor-ctime.a
 
 # Variants of the above for linking the testing variant of tor (for coverage
@@ -56,6 +57,7 @@ TOR_UTIL_TESTING_LIBS = \
 	src/lib/libtor-malloc-testing.a \
         src/lib/libtor-wallclock-testing.a \
         src/lib/libtor-err-testing.a \
+        src/lib/libtor-intmath.a \
         src/lib/libtor-ctime-testing.a
 
 # Internal crypto libraries used in Tor

src/common/util.c

@@ -166,105 +166,6 @@ tor_llround(double d)
 #endif /* defined(HAVE_LLROUND) || ... */
 }
 
-/** Returns floor(log2(u64)).  If u64 is 0, (incorrectly) returns 0. */
-int
-tor_log2(uint64_t u64)
-{
-  int r = 0;
-  if (u64 >= (U64_LITERAL(1)<<32)) {
-    u64 >>= 32;
-    r = 32;
-  }
-  if (u64 >= (U64_LITERAL(1)<<16)) {
-    u64 >>= 16;
-    r += 16;
-  }
-  if (u64 >= (U64_LITERAL(1)<<8)) {
-    u64 >>= 8;
-    r += 8;
-  }
-  if (u64 >= (U64_LITERAL(1)<<4)) {
-    u64 >>= 4;
-    r += 4;
-  }
-  if (u64 >= (U64_LITERAL(1)<<2)) {
-    u64 >>= 2;
-    r += 2;
-  }
-  if (u64 >= (U64_LITERAL(1)<<1)) {
-    // u64 >>= 1; // not using this any more.
-    r += 1;
-  }
-  return r;
-}
-
-/** Return the power of 2 in range [1,UINT64_MAX] closest to <b>u64</b>.  If
- * there are two powers of 2 equally close, round down. */
-uint64_t
-round_to_power_of_2(uint64_t u64)
-{
-  int lg2;
-  uint64_t low;
-  uint64_t high;
-  if (u64 == 0)
-    return 1;
-
-  lg2 = tor_log2(u64);
-  low = U64_LITERAL(1) << lg2;
-
-  if (lg2 == 63)
-    return low;
-
-  high = U64_LITERAL(1) << (lg2+1);
-  if (high - u64 < u64 - low)
-    return high;
-  else
-    return low;
-}
-
-/** Return the lowest x such that x is at least <b>number</b>, and x modulo
- * <b>divisor</b> == 0.  If no such x can be expressed as an unsigned, return
- * UINT_MAX. Asserts if divisor is zero. */
-unsigned
-round_to_next_multiple_of(unsigned number, unsigned divisor)
-{
-  tor_assert(divisor > 0);
-  if (UINT_MAX - divisor + 1 < number)
-    return UINT_MAX;
-  number += divisor - 1;
-  number -= number % divisor;
-  return number;
-}
-
-/** Return the lowest x such that x is at least <b>number</b>, and x modulo
- * <b>divisor</b> == 0. If no such x can be expressed as a uint32_t, return
- * UINT32_MAX. Asserts if divisor is zero. */
-uint32_t
-round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor)
-{
-  tor_assert(divisor > 0);
-  if (UINT32_MAX - divisor + 1 < number)
-    return UINT32_MAX;
-
-  number += divisor - 1;
-  number -= number % divisor;
-  return number;
-}
-
-/** Return the lowest x such that x is at least <b>number</b>, and x modulo
- * <b>divisor</b> == 0. If no such x can be expressed as a uint64_t, return
- * UINT64_MAX. Asserts if divisor is zero. */
-uint64_t
-round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor)
-{
-  tor_assert(divisor > 0);
-  if (UINT64_MAX - divisor + 1 < number)
-    return UINT64_MAX;
-  number += divisor - 1;
-  number -= number % divisor;
-  return number;
-}
-
 /** Transform a random value <b>p</b> from the uniform distribution in
  * [0.0, 1.0[ into a Laplace distributed value with location parameter
  * <b>mu</b> and scale parameter <b>b</b>. Truncate the final result
@@ -319,68 +220,6 @@ add_laplace_noise(int64_t signal_, double random_, double delta_f,
     return signal_ + noise;
 }
 
-/* Helper: safely add two uint32_t's, capping at UINT32_MAX rather
- * than overflow */
-uint32_t
-tor_add_u32_nowrap(uint32_t a, uint32_t b)
-{
-  /* a+b > UINT32_MAX check, without overflow */
-  if (PREDICT_UNLIKELY(a > UINT32_MAX - b)) {
-    return UINT32_MAX;
-  } else {
-    return a+b;
-  }
-}
-
-/* Helper: return greatest common divisor of a,b */
-static uint64_t
-gcd64(uint64_t a, uint64_t b)
-{
-  while (b) {
-    uint64_t t = b;
-    b = a % b;
-    a = t;
-  }
-  return a;
-}
-
-/* Given a fraction *<b>numer</b> / *<b>denom</b>, simplify it.
- * Requires that the denominator is greater than 0. */
-void
-simplify_fraction64(uint64_t *numer, uint64_t *denom)
-{
-  tor_assert(denom);
-  uint64_t gcd = gcd64(*numer, *denom);
-  *numer /= gcd;
-  *denom /= gcd;
-}
-
-/** Return the number of bits set in <b>v</b>. */
-int
-n_bits_set_u8(uint8_t v)
-{
-  static const int nybble_table[] = {
-    0, /* 0000 */
-    1, /* 0001 */
-    1, /* 0010 */
-    2, /* 0011 */
-    1, /* 0100 */
-    2, /* 0101 */
-    2, /* 0110 */
-    3, /* 0111 */
-    1, /* 1000 */
-    2, /* 1001 */
-    2, /* 1010 */
-    3, /* 1011 */
-    2, /* 1100 */
-    3, /* 1101 */
-    3, /* 1110 */
-    4, /* 1111 */
-  };
-
-  return nybble_table[v & 15] + nybble_table[v>>4];
-}
-
 /* =====
  * String manipulation
  * ===== */

src/common/util.h

@@ -27,6 +27,10 @@
 #include "lib/wallclock/approx_time.h"
 #include "lib/string/util_string.h"
 #include "lib/string/scanf.h"
+#include "lib/intmath/bits.h"
+#include "lib/intmath/addsub.h"
+#include "lib/intmath/muldiv.h"
+#include "lib/intmath/cmp.h"
 #include "common/util_bug.h"
 
 #ifndef O_BINARY
@@ -66,35 +70,10 @@ void tor_log_mallinfo(int severity);
 double tor_mathlog(double d) ATTR_CONST;
 long tor_lround(double d) ATTR_CONST;
 int64_t tor_llround(double d) ATTR_CONST;
-int tor_log2(uint64_t u64) ATTR_CONST;
-uint64_t round_to_power_of_2(uint64_t u64);
-unsigned round_to_next_multiple_of(unsigned number, unsigned divisor);
-uint32_t round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor);
-uint64_t round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor);
 int64_t sample_laplace_distribution(double mu, double b, double p);
 int64_t add_laplace_noise(int64_t signal, double random, double delta_f,
                           double epsilon);
-int n_bits_set_u8(uint8_t v);
 int64_t clamp_double_to_int64(double number);
-void simplify_fraction64(uint64_t *numer, uint64_t *denom);
-
-uint32_t tor_add_u32_nowrap(uint32_t a, uint32_t b);
-
-/* Compute the CEIL of <b>a</b> divided by <b>b</b>, for nonnegative <b>a</b>
- * and positive <b>b</b>.  Works on integer types only. Not defined if a+(b-1)
- * can overflow. */
-#define CEIL_DIV(a,b) (((a)+((b)-1))/(b))
-
-/* Return <b>v</b> if it's between <b>min</b> and <b>max</b>.  Otherwise
- * return <b>min</b> if <b>v</b> is smaller than <b>min</b>, or <b>max</b> if
- * <b>b</b> is larger than <b>max</b>.
- *
- * Requires that <b>min</b> is no more than <b>max</b>. May evaluate any of
- * its arguments more than once! */
-#define CLAMP(min,v,max)                        \
-  ( ((v) < (min)) ? (min) :                     \
-    ((v) > (max)) ? (max) :                     \
-    (v) )
 
 /* String manipulation */
 

src/include.am

@@ -7,6 +7,7 @@ include src/lib/container/include.am
 include src/lib/crypt_ops/include.am
 include src/lib/defs/include.am
 include src/lib/include.libdonna.am
+include src/lib/intmath/include.am
 include src/lib/malloc/include.am
 include src/lib/string/include.am
 include src/lib/testsupport/include.am

src/lib/container/.may_include

@@ -7,10 +7,10 @@ lib/malloc/*.h
 lib/err/*.h
 lib/string/*.h
 lib/testsupport/testsupport.h
+lib/intmath/*.h
 
 ht.h
 siphash.h
 
 # XXX I'd like to remove this.
-common/util.h
 common/util_bug.h

src/lib/container/bloomfilt.c

@@ -14,7 +14,7 @@
 #include <stdlib.h>
 #include "lib/malloc/util_malloc.h"
 #include "lib/container/bloomfilt.h"
-#include "common/util.h" // For tor_log2
+#include "lib/intmath/bits.h"
 
 /** Return a newly allocated digestset_t, optimized to hold a total of
  * <b>max_elements</b> digests with a reasonably low false positive weight. */

src/lib/crypt_ops/.may_include

@@ -6,6 +6,7 @@ lib/ctime/*.h
 lib/defs/*.h
 lib/malloc/*.h
 lib/err/*.h
+lib/intmath/*.h
 lib/string/*.h
 lib/testsupport/testsupport.h
 

src/lib/crypt_ops/crypto_pwbox.c

@@ -15,6 +15,7 @@
 #include "lib/crypt_ops/crypto_s2k.h"
 #include "lib/crypt_ops/crypto_util.h"
 #include "lib/ctime/di_ops.h"
+#include "lib/intmath/muldiv.h"
 #include "common/util.h"
 #include "trunnel/pwbox.h"
 
@@ -212,4 +213,3 @@ crypto_unpwbox(uint8_t **out, size_t *outlen_out,
   memwipe(keys, 0, sizeof(keys));
   return rv;
 }
-

src/lib/intmath/.may_include

@@ -0,0 +1,4 @@
+orconfig.h
+lib/cc/*.h
+lib/err/*.h
+lib/intmath/*.h

src/lib/intmath/addsub.c

@@ -0,0 +1,20 @@
+/* Copyright (c) 2003-2004, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "lib/intmath/addsub.h"
+#include "lib/cc/compat_compiler.h"
+
+/* Helper: safely add two uint32_t's, capping at UINT32_MAX rather
+ * than overflow */
+uint32_t
+tor_add_u32_nowrap(uint32_t a, uint32_t b)
+{
+  /* a+b > UINT32_MAX check, without overflow */
+  if (PREDICT_UNLIKELY(a > UINT32_MAX - b)) {
+    return UINT32_MAX;
+  } else {
+    return a+b;
+  }
+}

src/lib/intmath/addsub.h

@@ -0,0 +1,13 @@
+/* Copyright (c) 2003-2004, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#ifndef TOR_INTMATH_ADDSUB_H
+#define TOR_INTMATH_ADDSUB_H
+
+#include "lib/cc/torint.h"
+
+uint32_t tor_add_u32_nowrap(uint32_t a, uint32_t b);
+
+#endif /* !defined(TOR_INTMATH_MULDIV_H) */