diff options
author | lloyd <[email protected]> | 2008-09-30 22:41:49 +0000 |
---|---|---|
committer | lloyd <[email protected]> | 2008-09-30 22:41:49 +0000 |
commit | 13d08cbe978c4cd0de01aa0120c39470508cbbcb (patch) | |
tree | ff93739131cbca0dbdf23a31cd4b7611faf5aa6e /src/math/bigint/mp_misc.cpp | |
parent | 8854fe339f2e1f81091ba65c042824e8cc62cbbc (diff) |
Rearrange BigInt directories:
math/bigint - BigInt implementation
math/numbertheory - Math stuff built on top of BigInt
Coming soon: math/gfp (parts of pk/ecdsa)
Update deps in the pk files
Diffstat (limited to 'src/math/bigint/mp_misc.cpp')
-rw-r--r-- | src/math/bigint/mp_misc.cpp | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/src/math/bigint/mp_misc.cpp b/src/math/bigint/mp_misc.cpp new file mode 100644 index 000000000..db9c8cda0 --- /dev/null +++ b/src/math/bigint/mp_misc.cpp @@ -0,0 +1,92 @@ +/************************************************* +* MP Misc Functions Source File * +* (C) 1999-2008 Jack Lloyd * +*************************************************/ + +#include <botan/mp_core.h> +#include <botan/mp_asm.h> + +namespace Botan { + +extern "C" { + +/************************************************* +* Core Division Operation * +*************************************************/ +u32bit bigint_divcore(word q, word y1, word y2, + word x1, word x2, word x3) + { + word y0 = 0; + y2 = word_madd2(q, y2, &y0); + y1 = word_madd2(q, y1, &y0); + + if(y0 > x1) return 1; + if(y0 < x1) return 0; + if(y1 > x2) return 1; + if(y1 < x2) return 0; + if(y2 > x3) return 1; + if(y2 < x3) return 0; + return 0; + } + +/************************************************* +* Compare two MP integers * +*************************************************/ +s32bit bigint_cmp(const word x[], u32bit x_size, + const word y[], u32bit y_size) + { + if(x_size < y_size) { return (-bigint_cmp(y, y_size, x, x_size)); } + + while(x_size > y_size) + { + if(x[x_size-1]) + return 1; + x_size--; + } + for(u32bit j = x_size; j > 0; --j) + { + if(x[j-1] > y[j-1]) return 1; + if(x[j-1] < y[j-1]) return -1; + } + return 0; + } + +/************************************************* +* Do a 2-word/1-word Division * +*************************************************/ +word bigint_divop(word n1, word n0, word d) + { + word high = n1 % d, quotient = 0; + + for(u32bit j = 0; j != MP_WORD_BITS; ++j) + { + word high_top_bit = (high & MP_WORD_TOP_BIT); + + high <<= 1; + high |= (n0 >> (MP_WORD_BITS-1-j)) & 1; + quotient <<= 1; + + if(high_top_bit || high >= d) + { + high -= d; + quotient |= 1; + } + } + + return quotient; + } + +/************************************************* +* Do a 2-word/1-word Modulo * +*************************************************/ +word bigint_modop(word n1, word n0, word d) + { + word z = bigint_divop(n1, n0, d); + word dummy = 0; + z = word_madd2(z, d, &dummy); + return (n0-z); + } + +} + +} |