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Force gcc to use x86's built-in 64/32->32,32 division instruction
[sgt/putty]
/
sshbn.c
diff --git
a/sshbn.c
b/sshbn.c
index
a51c3a5
..
3742227
100644
(file)
--- a/
sshbn.c
+++ b/
sshbn.c
@@
-15,6
+15,10
@@
typedef unsigned long long BignumDblInt;
#define BIGNUM_TOP_BIT 0x80000000UL
#define BIGNUM_INT_BITS 32
#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
#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))
#else
typedef unsigned short BignumInt;
typedef unsigned long BignumDblInt;
#else
typedef unsigned short BignumInt;
typedef unsigned long BignumDblInt;
@@
-22,6
+26,11
@@
typedef unsigned long BignumDblInt;
#define BIGNUM_TOP_BIT 0x8000U
#define BIGNUM_INT_BITS 16
#define MUL_WORD(w1, w2) ((BignumDblInt)w1 * w2)
#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)
#endif
#define BIGNUM_INT_BYTES (BIGNUM_INT_BITS / 8)
@@
-175,13
+184,11
@@
static void internal_mod(BignumInt *a, int alen,
ai1 = a[i + 1];
/* Find q = h:a[i] / m0 */
ai1 = a[i + 1];
/* Find q = h:a[i] / m0 */
- t = ((BignumDblInt) h << BIGNUM_INT_BITS) + a[i];
- q = t / m0;
- r = t % m0;
+ DIVMOD_WORD(q, r, h, a[i], m0);
/* Refine our estimate of q by looking at
h:a[i]:a[i+1] / m0:m1 */
/* Refine our estimate of q by looking at
h:a[i]:a[i+1] / m0:m1 */
- t =
(BignumDblInt) m1 * (BignumDblInt) q
;
+ t =
MUL_WORD(m1, q)
;
if (t > ((BignumDblInt) r << BIGNUM_INT_BITS) + ai1) {
q--;
t -= m1;
if (t > ((BignumDblInt) r << BIGNUM_INT_BITS) + ai1) {
q--;
t -= m1;
@@
-193,7
+200,7
@@
static void internal_mod(BignumInt *a, int alen,
/* Subtract q * m from a[i...] */
c = 0;
for (k = mlen - 1; k >= 0; k--) {
/* Subtract q * m from a[i...] */
c = 0;
for (k = mlen - 1; k >= 0; k--) {
- t =
(BignumDblInt) q * (BignumDblInt) m[k]
;
+ t =
MUL_WORD(q, m[k])
;
t += c;
c = t >> BIGNUM_INT_BITS;
if ((BignumInt) t > a[i + k])
t += c;
c = t >> BIGNUM_INT_BITS;
if ((BignumInt) t > a[i + k])