From 37da2899f40661e3e9631e497da8dc59b971cbd0 Mon Sep 17 00:00:00 2001 From: "Charles.Forsyth" Date: Fri, 22 Dec 2006 17:07:39 +0000 Subject: 20060303a --- libmp/port/betomp.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 libmp/port/betomp.c (limited to 'libmp/port/betomp.c') diff --git a/libmp/port/betomp.c b/libmp/port/betomp.c new file mode 100644 index 00000000..95935fcd --- /dev/null +++ b/libmp/port/betomp.c @@ -0,0 +1,40 @@ +#include "os.h" +#include +#include "dat.h" + +// convert a big-endian byte array (most significant byte first) to an mpint +mpint* +betomp(uchar *p, uint n, mpint *b) +{ + int m, s; + mpdigit x; + + if(b == nil) + b = mpnew(0); + + // dump leading zeros + while(*p == 0 && n > 1){ + p++; + n--; + } + + // get the space + mpbits(b, n*8); + b->top = DIGITS(n*8); + m = b->top-1; + + // first digit might not be Dbytes long + s = ((n-1)*8)%Dbits; + x = 0; + for(; n > 0; n--){ + x |= ((mpdigit)(*p++)) << s; + s -= 8; + if(s < 0){ + b->p[m--] = x; + s = Dbits-8; + x = 0; + } + } + + return b; +} -- cgit v1.2.3