Move BignumInt definitions into a header file.

This allows files other than sshbn.c to work with the primitives
necessary to build multi-word arithmetic functions satisfying all of
PuTTY's portability constraints.

diff --git a/sshbn.c b/sshbn.c
index f2a28e00f5f9e15623d864edb4c7b8f652ca1e47..e1abbb05697eda4e48719cbea713707f29a0e512 100644 (file)
--- a/sshbn.c
+++ b/sshbn.c
@@ -11,90 +11,7 @@
 
 #include "misc.h"
 
-/*
- * Usage notes:
- *  * Do not call the DIVMOD_WORD macro with expressions such as array
- *    subscripts, as some implementations object to this (see below).
- *  * Note that none of the division methods below will cope if the
- *    quotient won't fit into BIGNUM_INT_BITS. Callers should be careful
- *    to avoid this case.
- *    If this condition occurs, in the case of the x86 DIV instruction,
- *    an overflow exception will occur, which (according to a correspondent)
- *    will manifest on Windows as something like
- *      0xC0000095: Integer overflow
- *    The C variant won't give the right answer, either.
- */
-
-#if defined __GNUC__ && defined __i386__
-typedef unsigned long BignumInt;
-typedef unsigned long long BignumDblInt;
-#define BIGNUM_INT_MASK  0xFFFFFFFFUL
-#define BIGNUM_TOP_BIT   0x80000000UL
-#define BIGNUM_INT_BITS  32
-#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
-#define DIVMOD_WORD(q, r, hi, lo, w) \
-    __asm__("div %2" : \
-           "=d" (r), "=a" (q) : \
-           "r" (w), "d" (hi), "a" (lo))
-#elif defined _MSC_VER && defined _M_IX86
-typedef unsigned __int32 BignumInt;
-typedef unsigned __int64 BignumDblInt;
-#define BIGNUM_INT_MASK  0xFFFFFFFFUL
-#define BIGNUM_TOP_BIT   0x80000000UL
-#define BIGNUM_INT_BITS  32
-#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
-/* Note: MASM interprets array subscripts in the macro arguments as
- * assembler syntax, which gives the wrong answer. Don't supply them.
- * <http://msdn2.microsoft.com/en-us/library/bf1dw62z.aspx> */
-#define DIVMOD_WORD(q, r, hi, lo, w) do { \
-    __asm mov edx, hi \
-    __asm mov eax, lo \
-    __asm div w \
-    __asm mov r, edx \
-    __asm mov q, eax \
-} while(0)
-#elif defined _LP64
-/* 64-bit architectures can do 32x32->64 chunks at a time */
-typedef unsigned int BignumInt;
-typedef unsigned long BignumDblInt;
-#define BIGNUM_INT_MASK  0xFFFFFFFFU
-#define BIGNUM_TOP_BIT   0x80000000U
-#define BIGNUM_INT_BITS  32
-#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
-#define DIVMOD_WORD(q, r, hi, lo, w) do { \
-    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
-    q = n / w; \
-    r = n % w; \
-} while (0)
-#elif defined _LLP64
-/* 64-bit architectures in which unsigned long is 32 bits, not 64 */
-typedef unsigned long BignumInt;
-typedef unsigned long long BignumDblInt;
-#define BIGNUM_INT_MASK  0xFFFFFFFFUL
-#define BIGNUM_TOP_BIT   0x80000000UL
-#define BIGNUM_INT_BITS  32
-#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
-#define DIVMOD_WORD(q, r, hi, lo, w) do { \
-    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
-    q = n / w; \
-    r = n % w; \
-} while (0)
-#else
-/* Fallback for all other cases */
-typedef unsigned short BignumInt;
-typedef unsigned long BignumDblInt;
-#define BIGNUM_INT_MASK  0xFFFFU
-#define BIGNUM_TOP_BIT   0x8000U
-#define BIGNUM_INT_BITS  16
-#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
-#define DIVMOD_WORD(q, r, hi, lo, w) do { \
-    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
-    q = n / w; \
-    r = n % w; \
-} while (0)
-#endif
-
-#define BIGNUM_INT_BYTES (BIGNUM_INT_BITS / 8)
+#include "sshbn.h"
 
 #define BIGNUM_INTERNAL
 typedef BignumInt *Bignum;

diff --git a/sshbn.h b/sshbn.h
new file mode 100644 (file)
index 0000000..3d15b94
--- /dev/null
+++ b/sshbn.h
@@ -0,0 +1,92 @@
+/*
+ * sshbn.h: the assorted conditional definitions of BignumInt and
+ * multiply/divide macros used throughout the bignum code to treat
+ * numbers as arrays of the most conveniently sized word for the
+ * target machine. Exported so that other code (e.g. poly1305) can use
+ * it too.
+ */
+
+/*
+ * Usage notes:
+ *  * Do not call the DIVMOD_WORD macro with expressions such as array
+ *    subscripts, as some implementations object to this (see below).
+ *  * Note that none of the division methods below will cope if the
+ *    quotient won't fit into BIGNUM_INT_BITS. Callers should be careful
+ *    to avoid this case.
+ *    If this condition occurs, in the case of the x86 DIV instruction,
+ *    an overflow exception will occur, which (according to a correspondent)
+ *    will manifest on Windows as something like
+ *      0xC0000095: Integer overflow
+ *    The C variant won't give the right answer, either.
+ */
+
+#if defined __GNUC__ && defined __i386__
+typedef unsigned long BignumInt;
+typedef unsigned long long BignumDblInt;
+#define BIGNUM_INT_MASK  0xFFFFFFFFUL
+#define BIGNUM_TOP_BIT   0x80000000UL
+#define BIGNUM_INT_BITS  32
+#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
+#define DIVMOD_WORD(q, r, hi, lo, w) \
+    __asm__("div %2" : \
+           "=d" (r), "=a" (q) : \
+           "r" (w), "d" (hi), "a" (lo))
+#elif defined _MSC_VER && defined _M_IX86
+typedef unsigned __int32 BignumInt;
+typedef unsigned __int64 BignumDblInt;
+#define BIGNUM_INT_MASK  0xFFFFFFFFUL
+#define BIGNUM_TOP_BIT   0x80000000UL
+#define BIGNUM_INT_BITS  32
+#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
+/* Note: MASM interprets array subscripts in the macro arguments as
+ * assembler syntax, which gives the wrong answer. Don't supply them.
+ * <http://msdn2.microsoft.com/en-us/library/bf1dw62z.aspx> */
+#define DIVMOD_WORD(q, r, hi, lo, w) do { \
+    __asm mov edx, hi \
+    __asm mov eax, lo \
+    __asm div w \
+    __asm mov r, edx \
+    __asm mov q, eax \
+} while(0)
+#elif defined _LP64
+/* 64-bit architectures can do 32x32->64 chunks at a time */
+typedef unsigned int BignumInt;
+typedef unsigned long BignumDblInt;
+#define BIGNUM_INT_MASK  0xFFFFFFFFU
+#define BIGNUM_TOP_BIT   0x80000000U
+#define BIGNUM_INT_BITS  32
+#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
+#define DIVMOD_WORD(q, r, hi, lo, w) do { \
+    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
+    q = n / w; \
+    r = n % w; \
+} while (0)
+#elif defined _LLP64
+/* 64-bit architectures in which unsigned long is 32 bits, not 64 */
+typedef unsigned long BignumInt;
+typedef unsigned long long BignumDblInt;
+#define BIGNUM_INT_MASK  0xFFFFFFFFUL
+#define BIGNUM_TOP_BIT   0x80000000UL
+#define BIGNUM_INT_BITS  32
+#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
+#define DIVMOD_WORD(q, r, hi, lo, w) do { \
+    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
+    q = n / w; \
+    r = n % w; \
+} while (0)
+#else
+/* Fallback for all other cases */
+typedef unsigned short BignumInt;
+typedef unsigned long BignumDblInt;
+#define BIGNUM_INT_MASK  0xFFFFU
+#define BIGNUM_TOP_BIT   0x8000U
+#define BIGNUM_INT_BITS  16
+#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
+#define DIVMOD_WORD(q, r, hi, lo, w) do { \
+    BignumDblInt n = (((BignumDblInt)hi) << BIGNUM_INT_BITS) | lo; \
+    q = n / w; \
+    r = n % w; \
+} while (0)
+#endif
+
+#define BIGNUM_INT_BYTES (BIGNUM_INT_BITS / 8)