Commit 9f607dd5eb20371e54dbf1cbb6fb653d88772818
2019-05-23T17:00:47
disallow defining MP_DIGIT_BIT, only allow MP_8/16/31/32/64BIT
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diff --git a/tommath.h b/tommath.h
index 329ddaa..51efb6e 100644
--- a/tommath.h
+++ b/tommath.h
@@ -43,6 +43,10 @@ extern "C" {
# endif
#endif
+#ifdef MP_DIGIT_BIT
+# error Defining MP_DIGIT_BIT is disallowed, use MP_8/16/31/32/64BIT
+#endif
+
/* some default configurations.
*
* A "mp_digit" must be able to hold MP_DIGIT_BIT + 1 bits
@@ -51,37 +55,35 @@ extern "C" {
* At the very least a mp_digit must be able to hold 7 bits
* [any size beyond that is ok provided it doesn't overflow the data type]
*/
+
#ifdef MP_8BIT
typedef uint8_t mp_digit;
typedef uint16_t private_mp_word;
-# define MP_SIZEOF_MP_DIGIT 1
-# ifdef MP_DIGIT_BIT
-# error You must not define MP_DIGIT_BIT when using MP_8BIT
-# endif
+# define MP_DIGIT_BIT 7
#elif defined(MP_16BIT)
typedef uint16_t mp_digit;
typedef uint32_t private_mp_word;
-# define MP_SIZEOF_MP_DIGIT 2
-# ifdef MP_DIGIT_BIT
-# error You must not define MP_DIGIT_BIT when using MP_16BIT
-# endif
+# define MP_DIGIT_BIT 15
#elif defined(MP_64BIT)
/* for GCC only on supported platforms */
typedef uint64_t mp_digit;
typedef unsigned long private_mp_word __attribute__((mode(TI)));
# define MP_DIGIT_BIT 60
#else
-/* this is the default case, 28-bit digits */
-
-/* this is to make porting into LibTomCrypt easier :-) */
typedef uint32_t mp_digit;
typedef uint64_t private_mp_word;
-
# ifdef MP_31BIT
-/* this is an extension that uses 31-bit digits */
+/*
+ * This is an extension that uses 31-bit digits.
+ * Please be aware that not all functions support this size, especially s_mp_mul_digs_fast
+ * will be reduced to work on small numbers only:
+ * Up to 8 limbs, 248 bits instead of up to 512 limbs, 15872 bits with MP_28BIT.
+ */
# define MP_DIGIT_BIT 31
# else
-/* default case is 28-bit digits, defines MP_28BIT as a handy macro to test */
+/* default case is 28-bit digits, defines MP_28BIT as a handy macro to test
+ * this is to make porting into LibTomCrypt easier :-)
+ */
# define MP_DIGIT_BIT 28
# define MP_28BIT
# endif
@@ -90,10 +92,7 @@ typedef uint64_t private_mp_word;
/* mp_word is a private type */
#define mp_word MP_DEPRECATED_PRAGMA("mp_word has been made private") private_mp_word
-/* otherwise the bits per digit is calculated automatically from the size of a mp_digit */
-#ifndef MP_DIGIT_BIT
-# define MP_DIGIT_BIT (((CHAR_BIT * MP_SIZEOF_MP_DIGIT) - 1)) /* bits per digit */
-#endif
+#define MP_SIZEOF_MP_DIGIT (MP_DEPRECATED_PRAGMA("MP_SIZEOF_MP_DIGIT has been deprecated, use sizeof (mp_digit)") sizeof (mp_digit))
#define MP_MASK ((((mp_digit)1)<<((mp_digit)MP_DIGIT_BIT))-((mp_digit)1))
#define MP_DIGIT_MAX MP_MASK