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Diffstat (limited to 'botan/src/math/bigint/mp_misc.cpp')
-rw-r--r-- | botan/src/math/bigint/mp_misc.cpp | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/botan/src/math/bigint/mp_misc.cpp b/botan/src/math/bigint/mp_misc.cpp new file mode 100644 index 0000000..6b7fc65 --- /dev/null +++ b/botan/src/math/bigint/mp_misc.cpp @@ -0,0 +1,94 @@ +/* +* MP Misc Functions +* (C) 1999-2008 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#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); + } + +} + +} |