Fix TFM mp_set_int to handle long. Enhance mp_set_int to use mp_set if less than max mp_digit. Added new MP_SET_CHUNK_BITS to eliminate hard coded const’s and allow build time adjustment.

wolfcrypt/src/integer.c

@@ -3903,25 +3903,32 @@ int fast_s_mp_mul_high_digs (mp_int * a, mp_int * b, mp_int * c, int digs)
 }
 
 
-/* set a 32-bit const */
+#ifndef MP_SET_CHUNK_BITS
+    #define MP_SET_CHUNK_BITS 4
+#endif
 int mp_set_int (mp_int * a, unsigned long b)
 {
-  int     x, res;
+  int x, res;
+
+  /* use direct mp_set if b is less than mp_digit max */
+  if (b < MP_DIGIT_MAX) {
+    return mp_set (a, b);
+  }
 
   mp_zero (a);
 
-  /* set four bits at a time */
+  /* set chunk bits at a time */
-  for (x = 0; x < 8; x++) {
+  for (x = 0; x < (int)(sizeof(long) * 8) / MP_SET_CHUNK_BITS; x++) {
-    /* shift the number up four bits */
+    /* shift the number up chunk bits */
-    if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
+    if ((res = mp_mul_2d (a, MP_SET_CHUNK_BITS, a)) != MP_OKAY) {
       return res;
     }
 
-    /* OR in the top four bits of the source */
+    /* OR in the top bits of the source */
-    a->dp[0] |= (b >> 28) & 15;
+    a->dp[0] |= (b >> (32 - MP_SET_CHUNK_BITS)) & ((1 << MP_SET_CHUNK_BITS) - 1);
 
-    /* shift the source up to the next four bits */
+    /* shift the source up to the next chunk bits */
-    b <<= 4;
+    b <<= MP_SET_CHUNK_BITS;
 
     /* ensure that digits are not clamped off */
     a->used += 1;

wolfcrypt/src/rsa.c

@@ -1484,7 +1484,7 @@ int wc_MakeRsaKey(RsaKey* key, int size, long e, WC_RNG* rng)
     if ((err = mp_init_multi(&p, &q, &tmp1, &tmp2, &tmp3, NULL)) != MP_OKAY)
         return err;
 
-    err = mp_set_int(&tmp3, (mp_digit)e);
+    err = mp_set_int(&tmp3, e);
 
     /* make p */
     if (err == MP_OKAY) {

wolfcrypt/src/tfm.c

@@ -1963,6 +1963,40 @@ void fp_set(fp_int *a, fp_digit b)
    a->used  = a->dp[0] ? 1 : 0;
 }
 
+
+#ifndef MP_SET_CHUNK_BITS
+    #define MP_SET_CHUNK_BITS 4
+#endif
+void fp_set_int(fp_int *a, unsigned long b)
+{
+  int x;
+
+  /* use direct fp_set if b is less than fp_digit max */
+  if (b < FP_DIGIT_MAX) {
+    fp_set (a, b);
+    return;
+  }
+
+  fp_zero (a);
+
+  /* set chunk bits at a time */
+  for (x = 0; x < (int)(sizeof(long) * 8) / MP_SET_CHUNK_BITS; x++) {
+    fp_mul_2d (a, MP_SET_CHUNK_BITS, a);
+
+    /* OR in the top bits of the source */
+    a->dp[0] |= (b >> (32 - MP_SET_CHUNK_BITS)) & ((1 << MP_SET_CHUNK_BITS) - 1);
+
+    /* shift the source up to the next chunk bits */
+    b <<= MP_SET_CHUNK_BITS;
+
+    /* ensure that digits are not clamped off */
+    a->used += 1;
+  }
+
+  /* clamp digits */
+  fp_clamp(a);
+}
+
 /* check if a bit is set */
 int fp_is_bit_set (fp_int *a, fp_digit b)
 {
@@ -2440,9 +2474,9 @@ void mp_rshd (mp_int* a, int x)
     fp_rshd(a, x);
 }
 
-int mp_set_int(mp_int *a, mp_digit b)
+int mp_set_int(mp_int *a, unsigned long b)
 {
-    fp_set(a, b);
+    fp_set_int(a, b);
     return MP_OKAY;
 }
 

wolfssl/wolfcrypt/tfm.h

@@ -260,6 +260,7 @@
 #endif
 
 #define FP_MASK    (fp_digit)(-1)
+#define FP_DIGIT_MAX FP_MASK
 #define FP_SIZE    (FP_MAX_SIZE/DIGIT_BIT)
 
 /* signs */
@@ -382,6 +383,7 @@ void fp_clear(fp_int *a); /* uses ForceZero to clear sensitive memory */
 
 /* set to a small digit */
 void fp_set(fp_int *a, fp_digit b);
+void fp_set_int(fp_int *a, unsigned long b);
 
 /* check if a bit is set */
 int fp_is_bit_set(fp_int *a, fp_digit b);
@@ -650,7 +652,7 @@ int  mp_isodd(mp_int* a);
 int  mp_iszero(mp_int* a);
 int  mp_count_bits(mp_int *a);
 int  mp_leading_bit(mp_int *a);
-int  mp_set_int(mp_int *a, mp_digit b);
+int  mp_set_int(mp_int *a, unsigned long b);
 int  mp_is_bit_set (mp_int * a, mp_digit b);
 int  mp_set_bit (mp_int * a, mp_digit b);
 void mp_rshb(mp_int *a, int x);