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275 lines
4.8 KiB
275 lines
4.8 KiB
diff --git a/ecc-256.c b/ecc-256.c |
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index 571cf73..07841b1 100644 |
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--- a/ecc-256.c |
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+++ b/ecc-256.c |
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@@ -108,7 +108,10 @@ ecc_256_modp (const struct ecc_curve *ecc, mp_limb_t *rp) |
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u0 -= t; |
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t = (u1 < cy); |
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u1 -= cy; |
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- u1 += cnd_add_n (t, rp + n - 4, ecc->p, 3); |
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+ |
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+ cy = cnd_add_n (t, rp + n - 4, ecc->p, 2); |
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+ u0 += cy; |
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+ u1 += (u0 < cy); |
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u1 -= (-t) & 0xffffffff; |
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} |
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rp[2] = u0; |
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@@ -195,7 +198,7 @@ ecc_256_modq (const struct ecc_curve *ecc, mp_limb_t *rp) |
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/* Conditional add of p */ |
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u1 += t; |
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- u2 += (t<<32) + (u0 < t); |
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+ u2 += (t<<32) + (u1 < t); |
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t = cnd_add_n (t, rp + n - 4, ecc->q, 2); |
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u1 += t; |
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diff --git a/x86_64/ecc-384-modp.asm b/x86_64/ecc-384-modp.asm |
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index 698838f..31b739e 100644 |
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--- a/x86_64/ecc-384-modp.asm |
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+++ b/x86_64/ecc-384-modp.asm |
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@@ -20,7 +20,7 @@ C MA 02111-1301, USA. |
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.file "ecc-384-modp.asm" |
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define(<RP>, <%rsi>) |
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-define(<D4>, <%rax>) |
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+define(<D5>, <%rax>) |
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define(<T0>, <%rbx>) |
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define(<T1>, <%rcx>) |
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define(<T2>, <%rdx>) |
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@@ -35,8 +35,8 @@ define(<H4>, <%r13>) |
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define(<H5>, <%r14>) |
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define(<C2>, <%r15>) |
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define(<C0>, H5) C Overlap |
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-define(<D0>, RP) C Overlap |
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-define(<TMP>, H4) C Overlap |
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+define(<TMP>, RP) C Overlap |
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+ |
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PROLOGUE(nettle_ecc_384_modp) |
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W64_ENTRY(2, 0) |
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@@ -48,34 +48,38 @@ PROLOGUE(nettle_ecc_384_modp) |
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push %r14 |
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push %r15 |
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- C First get top 2 limbs, which need folding twice |
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+ C First get top 2 limbs, which need folding twice. |
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+ C B^10 = B^6 + B^4 + 2^32 (B-1)B^4. |
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+ C We handle the terms as follow: |
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C |
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- C H5 H4 |
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- C -H5 |
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- C ------ |
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- C H0 D4 |
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+ C B^6: Folded immediatly. |
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C |
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- C Then shift right, (H1,H0,D4) <-- (H0,D4) << 32 |
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- C and add |
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+ C B^4: Delayed, added in in the next folding. |
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C |
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- C H5 H4 |
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- C H1 H0 |
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- C ---------- |
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- C C2 H1 H0 |
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- |
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- mov 80(RP), D4 |
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- mov 88(RP), H0 |
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- mov D4, H4 |
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- mov H0, H5 |
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- sub H0, D4 |
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- sbb $0, H0 |
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- |
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- mov D4, T2 |
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- mov H0, H1 |
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- shl $32, H0 |
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- shr $32, T2 |
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+ C 2^32(B-1) B^4: Low half limb delayed until the next |
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+ C folding. Top 1.5 limbs subtracted and shifter now, resulting |
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+ C in 2.5 limbs. The low limb saved in D5, high 1.5 limbs added |
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+ C in. |
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+ |
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+ mov 80(RP), H4 |
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+ mov 88(RP), H5 |
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+ C Shift right 32 bits, into H1, H0 |
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+ mov H4, H0 |
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+ mov H5, H1 |
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+ mov H5, D5 |
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shr $32, H1 |
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- or T2, H0 |
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+ shl $32, D5 |
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+ shr $32, H0 |
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+ or D5, H0 |
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+ |
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+ C H1 H0 |
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+ C - H1 H0 |
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+ C -------- |
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+ C H1 H0 D5 |
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+ mov H0, D5 |
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+ neg D5 |
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+ sbb H1, H0 |
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+ sbb $0, H1 |
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xor C2, C2 |
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add H4, H0 |
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@@ -114,118 +118,95 @@ PROLOGUE(nettle_ecc_384_modp) |
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adc H3, T5 |
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adc $0, C0 |
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- C H3 H2 H1 H0 0 |
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- C - H4 H3 H2 H1 H0 |
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- C --------------- |
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- C H3 H2 H1 H0 D0 |
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- |
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- mov XREG(D4), XREG(D4) |
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- mov H0, D0 |
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- neg D0 |
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- sbb H1, H0 |
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- sbb H2, H1 |
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- sbb H3, H2 |
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- sbb H4, H3 |
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- sbb $0, D4 |
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- |
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- C Shift right. High bits are sign, to be added to C0. |
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- mov D4, TMP |
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- sar $32, TMP |
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- shl $32, D4 |
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- add TMP, C0 |
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- |
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+ C Shift left, including low half of H4 |
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mov H3, TMP |
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+ shl $32, H4 |
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shr $32, TMP |
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- shl $32, H3 |
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- or TMP, D4 |
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+ or TMP, H4 |
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mov H2, TMP |
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+ shl $32, H3 |
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shr $32, TMP |
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- shl $32, H2 |
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or TMP, H3 |
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mov H1, TMP |
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+ shl $32, H2 |
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shr $32, TMP |
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- shl $32, H1 |
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or TMP, H2 |
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mov H0, TMP |
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+ shl $32, H1 |
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shr $32, TMP |
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- shl $32, H0 |
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or TMP, H1 |
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- mov D0, TMP |
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- shr $32, TMP |
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- shl $32, D0 |
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- or TMP, H0 |
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+ shl $32, H0 |
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+ |
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+ C H4 H3 H2 H1 H0 0 |
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+ C - H4 H3 H2 H1 H0 |
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+ C --------------- |
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+ C H4 H3 H2 H1 H0 TMP |
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- add D0, T0 |
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+ mov H0, TMP |
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+ neg TMP |
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+ sbb H1, H0 |
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+ sbb H2, H1 |
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+ sbb H3, H2 |
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+ sbb H4, H3 |
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+ sbb $0, H4 |
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+ |
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+ add TMP, T0 |
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adc H0, T1 |
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adc H1, T2 |
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adc H2, T3 |
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adc H3, T4 |
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- adc D4, T5 |
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+ adc H4, T5 |
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adc $0, C0 |
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C Remains to add in C2 and C0 |
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- C C0 C0<<32 (-2^32+1)C0 |
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- C C2 C2<<32 (-2^32+1)C2 |
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- C where C2 is always positive, while C0 may be -1. |
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+ C Set H1, H0 = (2^96 - 2^32 + 1) C0 |
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mov C0, H0 |
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mov C0, H1 |
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- mov C0, H2 |
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- sar $63, C0 C Get sign |
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shl $32, H1 |
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- sub H1, H0 C Gives borrow iff C0 > 0 |
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+ sub H1, H0 |
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sbb $0, H1 |
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- add C0, H2 |
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+ C Set H3, H2 = (2^96 - 2^32 + 1) C2 |
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+ mov C2, H2 |
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+ mov C2, H3 |
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+ shl $32, H3 |
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+ sub H3, H2 |
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+ sbb $0, H3 |
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+ add C0, H2 C No carry. Could use lea trick |
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+ |
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+ xor C0, C0 |
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add H0, T0 |
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adc H1, T1 |
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- adc $0, H2 |
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- adc $0, C0 |
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- |
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- C Set (H1 H0) <-- C2 << 96 - C2 << 32 + 1 |
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- mov C2, H0 |
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- mov C2, H1 |
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- shl $32, H1 |
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- sub H1, H0 |
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- sbb $0, H1 |
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- |
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- add H2, H0 |
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- adc C0, H1 |
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- adc C2, C0 |
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- mov C0, H2 |
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- sar $63, C0 |
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- add H0, T2 |
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- adc H1, T3 |
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- adc H2, T4 |
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- adc C0, T5 |
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- sbb C0, C0 |
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+ adc H2, T2 |
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+ adc H3, T3 |
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+ adc C2, T4 |
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+ adc D5, T5 C Value delayed from initial folding |
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+ adc $0, C0 C Use sbb and switch sign? |
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C Final unlikely carry |
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mov C0, H0 |
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mov C0, H1 |
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- mov C0, H2 |
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- sar $63, C0 |
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shl $32, H1 |
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sub H1, H0 |
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sbb $0, H1 |
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- add C0, H2 |
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pop RP |
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- sub H0, T0 |
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+ add H0, T0 |
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mov T0, (RP) |
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- sbb H1, T1 |
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+ adc H1, T1 |
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mov T1, 8(RP) |
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- sbb H2, T2 |
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+ adc C0, T2 |
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mov T2, 16(RP) |
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- sbb C0, T3 |
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+ adc $0, T3 |
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mov T3, 24(RP) |
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- sbb C0, T4 |
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+ adc $0, T4 |
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mov T4, 32(RP) |
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- sbb C0, T5 |
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+ adc $0, T5 |
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mov T5, 40(RP) |
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pop %r15
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