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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
// ----------------------------------------------------------------------------
// Square, z := x^2
// Input x[4]; output z[8]
//
// extern void bignum_sqr_4_8_alt
// (uint64_t z[static 8], uint64_t x[static 4]);
//
// Standard x86-64 ABI: RDI = z, RSI = x
// Microsoft x64 ABI: RCX = z, RDX = x
// ----------------------------------------------------------------------------
#include "s2n_bignum_internal.h"
.intel_syntax noprefix
S2N_BN_SYM_VISIBILITY_DIRECTIVE(bignum_sqr_4_8_alt)
S2N_BN_SYM_PRIVACY_DIRECTIVE(bignum_sqr_4_8_alt)
.text
// Input arguments
#define z rdi
#define x rsi
// Other variables used as a rotating 3-word window to add terms to
#define t0 rcx
#define t1 r8
#define t2 r9
// Macro for the key "multiply and add to (c,h,l)" step, for square term
#define combadd1(c,h,l,numa) \
mov rax, numa; \
mul rax; \
add l, rax; \
adc h, rdx; \
adc c, 0
// A short form where we don't expect a top carry
#define combads(h,l,numa) \
mov rax, numa; \
mul rax; \
add l, rax; \
adc h, rdx
// A version doubling before adding, for non-square terms
#define combadd2(c,h,l,numa,numb) \
mov rax, numa; \
mul QWORD PTR numb; \
add rax, rax; \
adc rdx, rdx; \
adc c, 0; \
add l, rax; \
adc h, rdx; \
adc c, 0
S2N_BN_SYMBOL(bignum_sqr_4_8_alt):
_CET_ENDBR
#if WINDOWS_ABI
push rdi
push rsi
mov rdi, rcx
mov rsi, rdx
#endif
// Result term 0
mov rax, [x]
mul rax
mov [z], rax
mov t0, rdx
xor t1, t1
// Result term 1
xor t2, t2
combadd2(t2,t1,t0,[x],[x+8])
mov [z+8], t0
// Result term 2
xor t0, t0
combadd1(t0,t2,t1,[x+8])
combadd2(t0,t2,t1,[x],[x+16])
mov [z+16], t1
// Result term 3
xor t1, t1
combadd2(t1,t0,t2,[x],[x+24])
combadd2(t1,t0,t2,[x+8],[x+16])
mov [z+24], t2
// Result term 4
xor t2, t2
combadd2(t2,t1,t0,[x+8],[x+24])
combadd1(t2,t1,t0,[x+16])
mov [z+32], t0
// Result term 5
xor t0, t0
combadd2(t0,t2,t1,[x+16],[x+24])
mov [z+40], t1
// Result term 6
xor t1, t1
combads(t0,t2,[x+24])
mov [z+48], t2
// Result term 7
mov [z+56], t0
// Return
#if WINDOWS_ABI
pop rsi
pop rdi
#endif
ret
#if defined(__linux__) && defined(__ELF__)
.section .note.GNU-stack,"",%progbits
#endif
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