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[crypto] Expose shifted out bit from big integer shifts

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Expose the bit shifted out as a result of shifting a big integer left
or right.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-02-13 14:18:15 +00:00
parent bd90abf487
commit 5056e8ad93
7 changed files with 146 additions and 85 deletions
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31
src/arch/arm64/include/bits/bigint.h
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@@ -122,14 +122,16 @@ bigint_subtract_raw ( const uint64_t *subtrahend0, uint64_t *value0,
*
* @v value0 Element 0 of big integer
* @v size Number of elements
* @ret out Bit shifted out
*/
static inline __attribute__ (( always_inline )) void
static inline __attribute__ (( always_inline )) int
bigint_shl_raw ( uint64_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint64_t *discard_value;
uint64_t discard_value_i;
unsigned int discard_size;
int carry;
__asm__ __volatile__ ( "cmn xzr, xzr\n\t" /* clear CF */
"\n1:\n\t"
@@ -141,9 +143,10 @@ bigint_shl_raw ( uint64_t *value0, unsigned int size ) {
: "=r" ( discard_value ),
"=r" ( discard_size ),
"=r" ( discard_value_i ),
"=@cccs" ( carry ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size )
: "cc" );
: "0" ( value0 ), "1" ( size ) );
return carry;
}
/**
@@ -151,30 +154,32 @@ bigint_shl_raw ( uint64_t *value0, unsigned int size ) {
*
* @v value0 Element 0 of big integer
* @v size Number of elements
* @ret out Bit shifted out
*/
static inline __attribute__ (( always_inline )) void
static inline __attribute__ (( always_inline )) int
bigint_shr_raw ( uint64_t *value0, unsigned int size ) {
bigint_t ( size ) __attribute__ (( may_alias )) *value =
( ( void * ) value0 );
uint64_t *discard_value;
uint64_t discard_value_i;
uint64_t discard_value_j;
uint64_t discard_high;
unsigned int discard_size;
uint64_t low;
__asm__ __volatile__ ( "mov %3, #0\n\t"
__asm__ __volatile__ ( "mov %2, #0\n\t"
"\n1:\n\t"
"sub %w1, %w1, #1\n\t"
"ldr %2, [%0, %1, lsl #3]\n\t"
"extr %3, %3, %2, #1\n\t"
"str %3, [%0, %1, lsl #3]\n\t"
"mov %3, %2\n\t"
"ldr %3, [%0, %1, lsl #3]\n\t"
"extr %2, %2, %3, #1\n\t"
"str %2, [%0, %1, lsl #3]\n\t"
"mov %2, %3\n\t"
"cbnz %w1, 1b\n\t"
: "=r" ( discard_value ),
"=r" ( discard_size ),
"=r" ( discard_value_i ),
"=r" ( discard_value_j ),
"=r" ( discard_high ),
"=r" ( low ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size ) );
return ( low & 1 );
}
/**