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https://github.com/yuzu-emu/mbedtls.git
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Optimise muladd more
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
This commit is contained in:
Kevin Bracey
parent
1959c18c69
commit
84f31d3eaa
173
tinycrypt/ecc.c
173
tinycrypt/ecc.c
@ -540,71 +540,75 @@ static void uECC_vli_rshift1(uECC_word_t *vli)
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}
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#endif
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/* Compute a * b + r, where r is a double-word with high-order word r1 and
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* low-order word r0, and store the result in the same double-word (r1, r0),
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* with the carry bit stored in r2.
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/* Compute a * b + r, where r is a triple-word with high-order word r[2] and
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* low-order word r[0], and store the result in the same triple-word.
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*
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* (r2, r1, r0) = a * b + (r1, r0):
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* r[2..0] = a * b + r[2..0]:
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* [in] a, b: operands to be multiplied
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* [in] r0, r1: low and high-order words of operand to add
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* [out] r0, r1: low and high-order words of the result
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* [out] r2: carry
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* [in] r: 3 words of operand to add
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* [out] r: 3 words of result
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*/
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#if defined MBEDTLS_HAVE_ASM && defined __CC_ARM
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static __asm void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t *r0,
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uECC_word_t *r1, uECC_word_t *r2)
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static __asm void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t r[3])
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{
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#if defined __thumb__ && __TARGET_ARCH_THUMB < 4
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IMPORT __ARM_common_ll_muluu
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PRESERVE8
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// have to save r4 to keep stack 8-byte aligned, but then
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// may as well make use of it - helps a bit having it
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PUSH {r2,r3,r4,lr}
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FRAME SAVE {r4,lr},-8
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FRAME ADDRESS sp,16
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BL __ARM_common_ll_muluu
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POP {r2,r3}
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FRAME ADDRESS sp,8
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LDR r4,[r2]
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ADDS r4,r0
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STR r4,[r2]
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LDR r4,[r3]
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PUSH {r4-r5}
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FRAME PUSH {r4-r5}
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// __ARM_common_mul_uu replacement - inline, faster, don't touch R2
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// Separate operands into halfwords
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UXTH r3,r0 // r3 := a.lo
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LSRS r4,r0,#16 // r4 := a.hi
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UXTH r5,r1 // r5 := b.lo
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LSRS r1,r1,#16 // r1 := b.hi
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// Multiply halfword pairs
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MOVS r0,r3
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MULS r0,r5,r0 // r0 := a.lo * b.lo
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MULS r3,r1,r3 // r3 := a.lo * b.hi
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MULS r5,r4,r5 // r5 := a.hi * b.lo
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MULS r1,r4,r1 // r1 := a.hi * b.hi
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// Split, shift and add a.lo * b.hi
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LSRS r4,r3,#16 // r4 := (a.lo * b.hi).hi
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LSLS r3,r3,#16 // r3 := (a.lo * b.hi).lo
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ADDS r0,r0,r3 // r0 := a.lo * b.lo + (a.lo * b.hi).lo
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ADCS r1,r4 // r1 := a.hi * b.hi + (a.lo * b.hi).hi + carry
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// Split, shift and add a.hi * b.lo
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LSRS r4,r5,#16 // r4 := (a.hi * b.lo).hi
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LSLS r5,r5,#16 // r5 := (a.hi * b.lo).lo
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ADDS r0,r0,r5 // r0 := a.lo * b.lo + (a.lo * b.hi).lo + (a.hi * b.lo).lo
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ADCS r1,r4 // r1 := a.hi * b.hi + (a.lo * b.hi).hi + (a.hi * b.lo).hi + carries
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// Finally add r[]
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LDMIA r2!,{r3,r4,r5}
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ADDS r3,r3,r0
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ADCS r4,r1
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STR r4,[r3]
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LDR r3,[sp,#8]
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LDR r4,[r3]
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MOVS r0,#0
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ADCS r4,r0
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STR r4,[r3]
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POP {r4,pc}
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ADCS r5,r0
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SUBS r2,#12
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STMIA r2!,{r3,r4,r5}
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POP {r4-r5}
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FRAME POP {r4-r5}
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BX lr
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#else
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UMULL r0,r1,r0,r1
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LDR ip,[r2]
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ADDS r0,r0,ip
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STR r0,[r2]
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LDR r0,[r3]
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ADCS r0,r1
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STR r0,[r3]
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LDR r3,[sp,#0]
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LDR r0,[r3]
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ADC r0,r0,#0
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STR r0,[r3]
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UMULL r3,ip,r0,r1 // pre-ARMv6 requires Rd[Lo|Hi] != Rn
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LDMIA r2,{r0,r1}
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ADDS r0,r0,r3
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LDR r3,[r2,#8]
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ADCS r1,r1,ip
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ADC r3,r3,#0
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STMIA r2!,{r0,r1,r3}
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BX lr
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#endif
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}
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#else
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static void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t *r0,
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uECC_word_t *r1, uECC_word_t *r2)
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static void muladd(uECC_word_t a, uECC_word_t b, uECC_word_t r[3])
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{
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uECC_dword_t p = (uECC_dword_t)a * b;
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uECC_dword_t r01 = ((uECC_dword_t)(*r1) << uECC_WORD_BITS) | *r0;
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uECC_dword_t r01 = ((uECC_dword_t)(r[1]) << uECC_WORD_BITS) | r[0];
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r01 += p;
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*r2 += (r01 < p);
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*r1 = r01 >> uECC_WORD_BITS;
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*r0 = (uECC_word_t)r01;
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r[2] += (r01 < p);
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r[1] = r01 >> uECC_WORD_BITS;
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r[0] = (uECC_word_t)r01;
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}
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#endif
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@ -663,16 +667,14 @@ static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
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const uECC_word_t *right, ecc_wait_state_t *s)
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{
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uECC_word_t r0 = 0;
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uECC_word_t r1 = 0;
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uECC_word_t r2 = 0;
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uECC_word_t r[3] = { 0, 0, 0 };
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wordcount_t i, k;
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const uint8_t num_words = NUM_ECC_WORDS;
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/* Fetch 8 bit worth of delay from the state; 0 if we have no state */
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uint8_t delays = s ? s->delays[s->i++] : 0;
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uECC_word_t rr0 = 0, rr1 = 0;
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volatile uECC_word_t r;
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uECC_word_t rr[3] = { 0, 0, 0 };
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volatile uECC_word_t rdummy;
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/* Mimic start of next loop: k in [0, 3] */
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k = 0 + (delays & 0x03);
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@ -680,24 +682,23 @@ static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
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/* k = 0 -> i in [1, 0] -> 0 extra muladd;
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* k = 3 -> i in [1, 3] -> 3 extra muladd */
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for (i = 1; i <= k; ++i) {
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muladd(left[i], right[k - i], &rr0, &rr1, &r2);
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muladd(left[i], right[k - i], rr);
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}
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r = rr0;
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rr0 = rr1;
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rr1 = r2;
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r2 = 0;
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rdummy = rr[0];
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rr[0] = rr[1];
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rr[1] = rr[2];
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rr[2] = 0;
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/* Compute each digit of result in sequence, maintaining the carries. */
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for (k = 0; k < num_words; ++k) {
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for (i = 0; i <= k; ++i) {
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muladd(left[i], right[k - i], &r0, &r1, &r2);
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muladd(left[i], right[k - i], r);
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}
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result[k] = r0;
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r0 = r1;
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r1 = r2;
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r2 = 0;
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result[k] = r[0];
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r[0] = r[1];
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r[1] = r[2];
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r[2] = 0;
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}
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/* Mimic end of previous loop: k in [4, 7] */
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@ -706,12 +707,12 @@ static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
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/* k = 4 -> i in [5, 4] -> 0 extra muladd;
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* k = 7 -> i in [5, 7] -> 3 extra muladd */
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for (i = 5; i <= k; ++i) {
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muladd(left[i], right[k - i], &rr0, &rr1, &r2);
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muladd(left[i], right[k - i], rr);
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}
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r = rr0;
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rr0 = rr1;
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rr1 = r2;
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r2 = 0;
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rdummy = rr[0];
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rr[0] = rr[1];
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rr[1] = rr[2];
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rr[2] = 0;
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/* Mimic start of next loop: k in [8, 11] */
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k = 11 - (delays & 0x03);
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@ -719,25 +720,25 @@ static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
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/* k = 8 -> i in [5, 7] -> 3 extra muladd;
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* k = 11 -> i in [8, 7] -> 0 extra muladd */
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for (i = (k + 5) - num_words; i < num_words; ++i) {
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muladd(left[i], right[k - i], &rr0, &rr1, &r2);
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muladd(left[i], right[k - i], rr);
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}
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r = rr0;
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rr0 = rr1;
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rr1 = r2;
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r2 = 0;
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rdummy = rr[0];
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rr[0] = rr[1];
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rr[1] = rr[2];
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rr[2] = 0;
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for (k = num_words; k < num_words * 2 - 1; ++k) {
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for (i = (k + 1) - num_words; i < num_words; ++i) {
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muladd(left[i], right[k - i], &r0, &r1, &r2);
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muladd(left[i], right[k - i], r);
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}
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result[k] = r0;
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r0 = r1;
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r1 = r2;
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r2 = 0;
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result[k] = r[0];
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r[0] = r[1];
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r[1] = r[2];
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r[2] = 0;
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}
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result[num_words * 2 - 1] = r0;
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result[num_words * 2 - 1] = r[0];
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/* Mimic end of previous loop: k in [12, 15] */
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k = 15 - (delays & 0x03);
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@ -745,15 +746,15 @@ static void uECC_vli_mult_rnd(uECC_word_t *result, const uECC_word_t *left,
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/* k = 12 -> i in [5, 7] -> 3 extra muladd;
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* k = 15 -> i in [8, 7] -> 0 extra muladd */
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for (i = (k + 1) - num_words; i < num_words; ++i) {
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muladd(left[i], right[k - i], &rr0, &rr1, &r2);
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muladd(left[i], right[k - i], rr);
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}
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r = rr0;
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rr0 = rr1;
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rr1 = r2;
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r2 = 0;
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rdummy = rr[0];
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rr[0] = rr[1];
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rr[1] = rr[2];
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rr[2] = 0;
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/* avoid warning that r is set but not used */
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(void) r;
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/* avoid warning that rdummy is set but not used */
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(void) rdummy;
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}
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void uECC_vli_modAdd(uECC_word_t *result, const uECC_word_t *left,
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