arm.txt

If developing for the ARM, or indeed any other new processor, you should 
first build a C-only library.

For the ARM, this mirdef.h header would be appropriate for an integer-
only build of the library.

--------------------------------------

/*
 *   MIRACL compiler/hardware definitions - mirdef.h
 */


#define MIRACL 32
#define MR_LITTLE_ENDIAN      

/* or possibly 
#define MR_BIG_ENDIAN      
*/

#define mr_utype int
#define MR_IBITS 32
#define MR_LBITS 32
#define mr_dltype long long
#define mr_unsign32 unsigned int
#define mr_unsign64 unsigned long long
#define MAXBASE ((mr_small)1<<(MIRACL-1))


#define MR_NOASM

---------------------------------------------

Assuming that the mirdef.h, miracl.h and mr*.c files are all in the same
directory, then a suitable batch file for building a MIRACL library might 
look like this:-

-------------------------------

armcc -I. -c -O2 mrcore.c
armcc -I. -c -O2 mrarth0.c
armcc -I. -c -O2 mrarth1.c
armcc -I. -c -O2 mrarth2.c
armcc -I. -c -O2 mralloc.c
armcc -I. -c -O2 mrsmall.c
armcc -I. -c -O2 mrio1.c
armcc -I. -c -O2 mrio2.c
armcc -I. -c -O2 mrgcd.c
armcc -I. -c -O2 mrjack.c
armcc -I. -c -O2 mrbits.c
armcc -I. -c -O2 mrxgcd.c
armcc -I. -c -O2 mrarth3.c
armcc -I. -c -O2 mrrand.c
armcc -I. -c -O2 mrprime.c
armcc -I. -c -O2 mrcrt.c
armcc -I. -c -O2 mrscrt.c
armcc -I. -c -O2 mrmonty.c
armcc -I. -c -O2 mrpower.c
armcc -I. -c -O2 mrsroot.c
armcc -I. -c -O2 mrcurve.c
armcc -I. -c -O2 mrfast.c
armcc -I. -c -O2 mrshs.c
armcc -I. -c -O2 mrshs256.c
armcc -I. -c -O2 mrshs512.c
armcc -I. -c -O2 mraes.c
armcc -I. -c -O2 mrgcm.c
armcc -I. -c -O2 mrlucas.c
armcc -I. -c -O2 mrstrong.c
armcc -I. -c -O2 mrbrick.c
armcc -I. -c -O2 mrebrick.c
armcc -I. -c -O2 mrgf2m.c
armcc -I. -c -O2 mrec2m.c
armcc -I. -c -O2 mrzzn2.c
armcc -I. -c -O2 mrzzn2b.c
armcc -I. -c -O2 mrzzn3.c
armcc -I. -c -O2 mrecn2.c
armar -rc miracl.a mrcore.o mrarth0.o mrarth1.o mrarth2.o mralloc.o mrsmall.o
armar -r  miracl.a mrio1.o mrio2.o mrjack.o mrgcd.o mrxgcd.o mrarth3.o mrgcm.o
armar -r  miracl.a mrrand.o mrprime.o mrcrt.o mrscrt.o mrmonty.o mrcurve.o 
armar -r  miracl.a mrfast.o mrshs.o mraes.o mrlucas.o mrstrong.o mrbrick.o 
armar -r  miracl.a mrebrick.o mrec2m.o mrgf2m.o mrpower.o mrsroot.o mrzzn2b.o
armar -r  miracl.a mrshs256.o mrshs512.o mrbits.o mrzzn2.o mrzzn3.o mrecn2.o
del mr*.o
armcc -I. -c pk-demo.c
armlink pk-demo.o miracl.a -o pk-demo.axf

--------------------------------------------

This may be fast enough for you. If its not you can use the assembly language
macros provided in arm.mcs or gccarm.mcs for greater speed. See kcmcomba.txt.

For faster RSA and DH implementations replace the MR_NOASM definition with
MR_KCM n (where n is usually 4, 8 or 16 - experiment. n*MIRACL must divide the 
modulus size in bits exactly, which it will for standard moduli of 1024 bit 
for example). Compile and run the utility mex.c

c:\miracl>mex n arm mrkcm

(Yes its the same n). Rebuild the MIRACL library, but this time include the 
modules mrkcm.c and mrmuldv.c (you can find the latter in mrmuldv.ccc This
standard C version will do.)

For fast GF(p) elliptic curves, replace MR_NOASM with MR_COMBA n. This time 
32*n is exactly the size of p in bits (assuming 32-bit processor).

This approach is also optimal for 1024-bit RSA decryption using the Chinese 
Remainder Theorem. Set n=16 (512=16*32)

c:\miracl>mex n arm mrcomba

Rebuild the MIRACL library, but this time include the modules mrcomba.c and 
mrmuldv.c.

Still not fast enough? If the prime p is of a "special" form for an Elliptic 
curve, define in mirdef.h MR_SPECIAL. Edit mrcomba.tpl to insert "special" code
for modular reduction - its quite easy and you will find examples there 
already. Run mex as before, and rebuild MIRACL again.


See ecdhp32.c for a worked example.


For processors other than the ARM, the basic procedure is the same. A C-only 
build is always possible. To go faster you will need to create a .mcs file 
for your processor, and then you can proceed as above.

An alternative is to do a C-only build and then go in and optimise the 
generated assembly language. The time-critical routines are usually 
multiply() and redc() which can be found in mrarth2.c and mrmonty.c

This will probably not be as fast as the highly optimised approach outlined
above.


NOTE: There is a nasty ARM compiler bug in the version I am using. It can 
cause problems, if for example using the C-only macros from c.mcs or c1.mcs

Use this program to illustrate the bug, or to see if your Compiler is 
affected.

/* Short program to illustrate ARM compiler bug
   works fine with -O0, gets wrong answer for -O1 and -O2 optimization 
   Answer should be 0xffffffff00000001 but it gets 0x1 
*/  

#include <stdio.h>

int main()
{
    unsigned long long x;
    unsigned long a,b;
    a=0;
    b=0xFFFFFFFF;
    x=(unsigned long long)a-b;
    printf("x= %llx\n",x);    
    return 0;
}


Another problem may arise with systems that do not fully support unsigned long 
long arithmetic (you may be getting linker errors with names like __udivdi3 
functions not found). In this case for a C only build delete the #define 
MR_NOASM from mirdef.h and use the blakely-sloan versions of mrmuldiv and 
mrmuldvm with the standard versions of mrmuldvd and mrmuldvd2 (from 
mrmuldv.ccc) to create a file mrmuldv.c which should then be included in the 
library. Also insert an #undef mr_dltype at the start of mrxgcd.c


If using GCC under winARM to build ARM application, try this example

/* Header mirdef.h */

#define MIRACL 32
#define MR_LITTLE_ENDIAN      
#define mr_utype int
#define MR_IBITS 32
#define MR_LBITS 32
#define mr_dltype long long
#define mr_unsign32 unsigned int
#define mr_unsign64 unsigned long long
#define MAXBASE ((mr_small)1<<(MIRACL-1))
#define MR_COMBA 6
#define MR_STATIC 6
#define MR_ALWAYS_BINARY
#define MR_STRIPPED_DOWN
#define MR_GENERIC_MT
#define MR_SPECIAL
#define MR_NO_STANDARD_IO 
#define MR_NO_FILE_IO


/* batch file */

mex 6 gccarm mrcomba
copy mrmuldv.ccc mrmuldv.c
arm-elf-gcc -I. -c -O2 mrcore.c
arm-elf-gcc -I. -c -O2 mrarth0.c
arm-elf-gcc -I. -c -O2 mrarth1.c
arm-elf-gcc -I. -c -O2 mrarth2.c
arm-elf-gcc -I. -c -O2 mrsmall.c
arm-elf-gcc -I. -c -O2 mrjack.c
arm-elf-gcc -I. -c -O2 mrbits.c
arm-elf-gcc -I. -c -O2 mrxgcd.c
arm-elf-gcc -I. -c -O2 mrmonty.c
arm-elf-gcc -I. -c -O2 mrsroot.c
arm-elf-gcc -I. -c -O2 mrcurve.c
arm-elf-gcc -I. -c -O2 mrlucas.c
arm-elf-gcc -I. -c -O2 mrebrick.c
arm-elf-gcc -I. -O2 -c mrcomba.c
arm-elf-gcc -I. -c -O2 mrmuldv.c

arm-elf-ar -rc miracl.a mrcore.o mrarth0.o mrarth1.o mrarth2.o mrsmall.o
arm-elf-ar -r  miracl.a mrjack.o mrxgcd.o 
arm-elf-ar -r  miracl.a mrmonty.o mrcurve.o 
arm-elf-ar -r  miracl.a mrebrick.o mrsroot.o mrlucas.o
arm-elf-ar -r  miracl.a mrbits.o mrcomba.o mrmuldv.o
del mr*.o
arm-elf-gcc -I. --debug -c  ecdhp.c
arm-elf-ld ecdhp.o miracl.a libgcc.a  -lc -lm -o ecdhp.axf