X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=tomsfastmath%2Fsrc%2Fbin%2Ffp_read_unsigned_bin.c;fp=tomsfastmath%2Fsrc%2Fbin%2Ffp_read_unsigned_bin.c;h=2ee89cba3e682adbbdac86efa480b9b2365e9ce3;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/tomsfastmath/src/bin/fp_read_unsigned_bin.c b/tomsfastmath/src/bin/fp_read_unsigned_bin.c
new file mode 100644
index 0000000..2ee89cb
--- /dev/null
+++ b/tomsfastmath/src/bin/fp_read_unsigned_bin.c
@@ -0,0 +1,66 @@
+/* TomsFastMath, a fast ISO C bignum library.
+ * 
+ * This project is meant to fill in where LibTomMath
+ * falls short.  That is speed ;-)
+ *
+ * This project is public domain and free for all purposes.
+ * 
+ * Tom St Denis, tomstdenis@gmail.com
+ */
+#include <tfm_private.h>
+
+void fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
+{
+  /* zero the int */
+  fp_zero (a);
+
+  /* If we know the endianness of this architecture, and we're using
+     32-bit fp_digits, we can optimize this */
+#if (defined(ENDIAN_LITTLE) || defined(ENDIAN_BIG)) && !defined(FP_64BIT)
+  /* But not for both simultaneously */
+#if defined(ENDIAN_LITTLE) && defined(ENDIAN_BIG)
+#error Both ENDIAN_LITTLE and ENDIAN_BIG defined.
+#endif
+  {
+     unsigned char *pd = (unsigned char *)a->dp;
+
+     if ((unsigned)c > (FP_SIZE * sizeof(fp_digit))) {
+        int excess = c - (FP_SIZE * sizeof(fp_digit));
+        c -= excess;
+        b += excess;
+     }
+     a->used = (c + sizeof(fp_digit) - 1)/sizeof(fp_digit);
+     /* read the bytes in */
+#ifdef ENDIAN_BIG
+     {
+       /* Use Duff's device to unroll the loop. */
+       int idx = (c - 1) & ~3;
+       switch (c % 4) {
+       case 0:	do { pd[idx+0] = *b++;
+       case 3:	     pd[idx+1] = *b++;
+       case 2:	     pd[idx+2] = *b++;
+       case 1:	     pd[idx+3] = *b++;
+                     idx -= 4;
+	 	        } while ((c -= 4) > 0);
+       }
+     }
+#else
+     for (c -= 1; c >= 0; c -= 1) {
+       pd[c] = *b++;
+     }
+#endif
+  }
+#else
+  /* read the bytes in */
+  for (; c > 0; c--) {
+     fp_mul_2d (a, 8, a);
+     a->dp[0] |= *b++;
+     a->used += 1;
+  }
+#endif
+  fp_clamp (a);
+}
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */