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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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22
src/arch/arm32/include/bits/bigint.h
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@@ -123,16 +123,18 @@ bigint_subtract_raw ( const uint32_t *subtrahend0, uint32_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 ( 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;
int carry;
__asm__ __volatile__ ( "adds %1, %0, %5, lsl #2\n\t" /* clear CF */
__asm__ __volatile__ ( "adds %1, %0, %1, lsl #2\n\t" /* clear CF */
"\n1:\n\t"
"ldr %2, [%0]\n\t"
"adcs %2, %2\n\t"
@@ -142,9 +144,10 @@ bigint_shl_raw ( uint32_t *value0, unsigned int size ) {
: "=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_value_i ),
"=@cccs" ( carry ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size )
: "cc" );
: "0" ( value0 ), "1" ( size ) );
return carry;
}
/**
@@ -152,16 +155,18 @@ bigint_shl_raw ( uint32_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 ( 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;
int carry;
__asm__ __volatile__ ( "adds %1, %0, %5, lsl #2\n\t" /* clear CF */
__asm__ __volatile__ ( "adds %1, %0, %1, lsl #2\n\t" /* clear CF */
"\n1:\n\t"
"ldmdb %1!, {%2}\n\t"
"rrxs %2, %2\n\t"
@@ -171,9 +176,10 @@ bigint_shr_raw ( uint32_t *value0, unsigned int size ) {
: "=l" ( discard_value ),
"=l" ( discard_end ),
"=l" ( discard_value_i ),
"=@cccs" ( carry ),
"+m" ( *value )
: "0" ( value0 ), "1" ( size )
: "cc" );
: "0" ( value0 ), "1" ( size ) );
return carry;
}
/**