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#ifndef _BITS_BIGINT_H
#define _BITS_BIGINT_H
/** @file
*
* Big integer support
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <string.h>
#include <strings.h>
/** Element of a big integer */
typedef uint32_t bigint_element_t;
/**
* Initialise big integer
*
* @v value0 Element 0 of big integer to initialise
* @v size Number of elements
* @v data Raw data
* @v len Length of raw data
*/
static inline __attribute__ (( always_inline )) void
bigint_init_raw ( uint32_t *value0, unsigned int size,
const void *data, size_t len ) {
size_t pad_len = ( sizeof ( bigint_t ( size ) ) - len );
uint8_t *value_byte = ( ( void * ) value0 );
const uint8_t *data_byte = ( data + len );
/* Copy raw data in reverse order, padding with zeros */
while ( len-- )
*(value_byte++) = *(--data_byte);
while ( pad_len-- )
*(value_byte++) = 0;
}
/**
* Add big integers
*
* @v addend0 Element 0 of big integer to add
* @v value0 Element 0 of big integer to be added to
* @v size Number of elements
* @ret carry Carry out
*/
static inline __attribute__ (( always_inline )) int
bigint_add_raw ( const uint32_t *addend0, uint32_t *value0,
unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint32_t *discard_addend;
uint32_t *discard_value;
uint32_t *discard_end;
uint32_t discard_addend_i;
uint32_t discard_value_i;
int carry;
__asm__ __volatile__ ( "adds %2, %0, %9, lsl #2\n\t" /* clear CF */
"\n1:\n\t"
"ldmia %0!, {%3}\n\t"
"ldr %4, [%1]\n\t"
"adcs %4, %3\n\t"
"stmia %1!, {%4}\n\t"
"teq %0, %2\n\t"
"bne 1b\n\t"
: "=l" ( discard_addend ),
"=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_addend_i ),
"=l" ( discard_value_i ),
"=@cccs" ( carry ),
"+m" ( *value )
: "0" ( addend0 ), "1" ( value0 ),
"l" ( size ) );
return carry;
}
/**
* Subtract big integers
*
* @v subtrahend0 Element 0 of big integer to subtract
* @v value0 Element 0 of big integer to be subtracted from
* @v size Number of elements
* @ret borrow Borrow out
*/
static inline __attribute__ (( always_inline )) int
bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_t *value0,
unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint32_t *discard_subtrahend;
uint32_t *discard_value;
uint32_t *discard_end;
uint32_t discard_subtrahend_i;
uint32_t discard_value_i;
int borrow;
__asm__ __volatile__ ( "add %2, %0, %9, lsl #2\n\t"
"cmp %2, %0\n\t" /* set CF */
"\n1:\n\t"
"ldmia %0!, {%3}\n\t"
"ldr %4, [%1]\n\t"
"sbcs %4, %3\n\t"
"stmia %1!, {%4}\n\t"
"teq %0, %2\n\t"
"bne 1b\n\t"
: "=l" ( discard_subtrahend ),
"=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_subtrahend_i ),
"=l" ( discard_value_i ),
"=@cccc" ( borrow ),
"+m" ( *value )
: "0" ( subtrahend0 ), "1" ( value0 ),
"l" ( size ) );
return borrow;
}
/**
* Shift big integer left
*
* @v value0 Element 0 of big integer
* @v size Number of elements
*/
static inline __attribute__ (( always_inline )) void
bigint_shl_raw ( uint32_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint32_t *discard_value;
uint32_t *discard_end;
uint32_t discard_value_i;
__asm__ __volatile__ ( "adds %1, %0, %5, lsl #2\n\t" /* clear CF */
"\n1:\n\t"
"ldr %2, [%0]\n\t"
"adcs %2, %2\n\t"
"stmia %0!, {%2}\n\t"
"teq %0, %1\n\t"
"bne 1b\n\t"
: "=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_value_i ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size )
: "cc" );
}
/**
* Shift big integer right
*
* @v value0 Element 0 of big integer
* @v size Number of elements
*/
static inline __attribute__ (( always_inline )) void
bigint_shr_raw ( uint32_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint32_t *discard_value;
uint32_t *discard_end;
uint32_t discard_value_i;
__asm__ __volatile__ ( "adds %1, %0, %5, lsl #2\n\t" /* clear CF */
"\n1:\n\t"
"ldmdb %1!, {%2}\n\t"
"rrxs %2, %2\n\t"
"str %2, [%1]\n\t"
"teq %0, %1\n\t"
"bne 1b\n\t"
: "=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_value_i ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size )
: "cc" );
}
/**
* Test if big integer is equal to zero
*
* @v value0 Element 0 of big integer
* @v size Number of elements
* @ret is_zero Big integer is equal to zero
*/
static inline __attribute__ (( always_inline, pure )) int
bigint_is_zero_raw ( const uint32_t *value0, unsigned int size ) {
const uint32_t *value = value0;
uint32_t value_i;
do {
value_i = *(value++);
if ( value_i )
break;
} while ( --size );
return ( value_i == 0 );
}
/**
* Compare big integers
*
* @v value0 Element 0 of big integer
* @v reference0 Element 0 of reference big integer
* @v size Number of elements
* @ret geq Big integer is greater than or equal to the reference
*/
static inline __attribute__ (( always_inline, pure )) int
bigint_is_geq_raw ( const uint32_t *value0, const uint32_t *reference0,
unsigned int size ) {
const uint32_t *value = ( value0 + size );
const uint32_t *reference = ( reference0 + size );
uint32_t value_i;
uint32_t reference_i;
do {
value_i = *(--value);
reference_i = *(--reference);
if ( value_i != reference_i )
break;
} while ( --size );
return ( value_i >= reference_i );
}
/**
* Find highest bit set in big integer
*
* @v value0 Element 0 of big integer
* @v size Number of elements
* @ret max_bit Highest bit set + 1 (or 0 if no bits set)
*/
static inline __attribute__ (( always_inline )) int
bigint_max_set_bit_raw ( const uint32_t *value0, unsigned int size ) {
const uint32_t *value = ( value0 + size );
int max_bit = ( 8 * sizeof ( bigint_t ( size ) ) );
uint32_t value_i;
do {
value_i = *(--value);
max_bit -= ( 32 - fls ( value_i ) );
if ( value_i )
break;
} while ( --size );
return max_bit;
}
/**
* Grow big integer
*
* @v source0 Element 0 of source big integer
* @v source_size Number of elements in source big integer
* @v dest0 Element 0 of destination big integer
* @v dest_size Number of elements in destination big integer
*/
static inline __attribute__ (( always_inline )) void
bigint_grow_raw ( const uint32_t *source0, unsigned int source_size,
uint32_t *dest0, unsigned int dest_size ) {
unsigned int pad_size = ( dest_size - source_size );
memcpy ( dest0, source0, sizeof ( bigint_t ( source_size ) ) );
memset ( ( dest0 + source_size ), 0, sizeof ( bigint_t ( pad_size ) ) );
}
/**
* Shrink big integer
*
* @v source0 Element 0 of source big integer
* @v source_size Number of elements in source big integer
* @v dest0 Element 0 of destination big integer
* @v dest_size Number of elements in destination big integer
*/
static inline __attribute__ (( always_inline )) void
bigint_shrink_raw ( const uint32_t *source0, unsigned int source_size __unused,
uint32_t *dest0, unsigned int dest_size ) {
memcpy ( dest0, source0, sizeof ( bigint_t ( dest_size ) ) );
}
/**
* Finalise big integer
*
* @v value0 Element 0 of big integer to finalise
* @v size Number of elements
* @v out Output buffer
* @v len Length of output buffer
*/
static inline __attribute__ (( always_inline )) void
bigint_done_raw ( const uint32_t *value0, unsigned int size __unused,
void *out, size_t len ) {
const uint8_t *value_byte = ( ( const void * ) value0 );
uint8_t *out_byte = ( out + len );
/* Copy raw data in reverse order */
while ( len-- )
*(--out_byte) = *(value_byte++);
}
/**
* Multiply big integer elements
*
* @v multiplicand Multiplicand element
* @v multiplier Multiplier element
* @v result Result element
* @v carry Carry element
*/
static inline __attribute__ (( always_inline )) void
bigint_multiply_one ( const uint32_t multiplicand, const uint32_t multiplier,
uint32_t *result, uint32_t *carry ) {
uint32_t discard_low;
uint32_t discard_high;
__asm__ __volatile__ ( /* Perform multiplication */
"umull %0, %1, %4, %5\n\t"
/* Accumulate result */
"adds %2, %0\n\t"
"adc %1, #0\n\t"
/* Accumulate carry (cannot overflow) */
"adds %2, %3\n\t"
"adc %3, %1, #0\n\t"
: "=r" ( discard_low ),
"=r" ( discard_high ),
"+r" ( *result ),
"+r" ( *carry )
: "r" ( multiplicand ),
"r" ( multiplier )
: "cc" );
}
#endif /* _BITS_BIGINT_H */
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