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authorlloyd <[email protected]>2008-09-30 22:41:49 +0000
committerlloyd <[email protected]>2008-09-30 22:41:49 +0000
commit13d08cbe978c4cd0de01aa0120c39470508cbbcb (patch)
treeff93739131cbca0dbdf23a31cd4b7611faf5aa6e /src/math/bigint/mp_misc.cpp
parent8854fe339f2e1f81091ba65c042824e8cc62cbbc (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.cpp92
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
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+++ b/src/math/bigint/mp_misc.cpp
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+/*************************************************
+* 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);
+ }
+
+}
+
+}