diff options
Diffstat (limited to 'openssl/doc/crypto/bn_internal.pod')
| -rw-r--r-- | openssl/doc/crypto/bn_internal.pod | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/openssl/doc/crypto/bn_internal.pod b/openssl/doc/crypto/bn_internal.pod index 891914678..91840b0f0 100644 --- a/openssl/doc/crypto/bn_internal.pod +++ b/openssl/doc/crypto/bn_internal.pod @@ -13,6 +13,8 @@ library internal functions =head1 SYNOPSIS + #include <openssl/bn.h> + BN_ULONG bn_mul_words(BN_ULONG *rp, BN_ULONG *ap, int num, BN_ULONG w); BN_ULONG bn_mul_add_words(BN_ULONG *rp, BN_ULONG *ap, int num, BN_ULONG w); @@ -70,24 +72,34 @@ applications. =head2 The BIGNUM structure - typedef struct bignum_st + typedef struct bignum_st BIGNUM; + + struct bignum_st { - int top; /* number of words used in d */ - BN_ULONG *d; /* pointer to an array containing the integer value */ - int max; /* size of the d array */ - int neg; /* sign */ - } BIGNUM; + BN_ULONG *d; /* Pointer to an array of 'BN_BITS2' bit chunks. */ + int top; /* Index of last used d +1. */ + /* The next are internal book keeping for bn_expand. */ + int dmax; /* Size of the d array. */ + int neg; /* one if the number is negative */ + int flags; + }; + The integer value is stored in B<d>, a malloc()ed array of words (B<BN_ULONG>), least significant word first. A B<BN_ULONG> can be either 16, 32 or 64 bits in size, depending on the 'number of bits' (B<BITS2>) specified in C<openssl/bn.h>. -B<max> is the size of the B<d> array that has been allocated. B<top> +B<dmax> is the size of the B<d> array that has been allocated. B<top> is the number of words being used, so for a value of 4, bn.d[0]=4 and bn.top=1. B<neg> is 1 if the number is negative. When a B<BIGNUM> is B<0>, the B<d> field can be B<NULL> and B<top> == B<0>. +B<flags> is a bit field of flags which are defined in C<openssl/bn.h>. The +flags begin with B<BN_FLG_>. The macros BN_set_flags(b,n) and +BN_get_flags(b,n) exist to enable or fetch flag(s) B<n> from B<BIGNUM> +structure B<b>. + Various routines in this library require the use of temporary B<BIGNUM> variables during their execution. Since dynamic memory allocation to create B<BIGNUM>s is rather expensive when used in @@ -207,12 +219,12 @@ significant non-zero word plus one when B<a> has shrunk. =head2 Debugging bn_check_top() verifies that C<((a)-E<gt>top E<gt>= 0 && (a)-E<gt>top -E<lt>= (a)-E<gt>max)>. A violation will cause the program to abort. +E<lt>= (a)-E<gt>dmax)>. A violation will cause the program to abort. bn_print() prints B<a> to stderr. bn_dump() prints B<n> words at B<d> (in reverse order, i.e. most significant word first) to stderr. -bn_set_max() makes B<a> a static number with a B<max> of its current size. +bn_set_max() makes B<a> a static number with a B<dmax> of its current size. This is used by bn_set_low() and bn_set_high() to make B<r> a read-only B<BIGNUM> that contains the B<n> low or high words of B<a>. |