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diff --git a/lib/libc/riscv/string/Makefile.inc b/lib/libc/riscv/string/Makefile.inc
--- a/lib/libc/riscv/string/Makefile.inc
+++ b/lib/libc/riscv/string/Makefile.inc
@@ -1,5 +1,6 @@
MDSRCS+= \
memchr.S \
+ memcpy.S \
memset.S \
strlen.S \
strrchr.S
diff --git a/lib/libc/riscv/string/memcpy.S b/lib/libc/riscv/string/memcpy.S
new file mode 100644
--- /dev/null
+++ b/lib/libc/riscv/string/memcpy.S
@@ -0,0 +1,217 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Strahinja Stanisic <strajabot@FreeBSD.org>
+ */
+
+#include <machine/asm.h>
+
+/*
+ * a0 - void* dst
+ * a1 - const void* src
+ * a2 - size_t len
+ */
+ENTRY(memcpy)
+ beqz a2, .Lreturn
+
+ /* diff = (dstv - srcv) & 0b111 */
+ sub t0, a0, a1
+ andi t0, t0, 0b111
+
+ sltiu t1, a2, 8
+
+ /* we never change a0, because memcpy returns the original dst */
+ mv a3, a0
+
+ /* len < 8 */
+ bnez t1, .Lend
+
+ /* t1 = (-dst) & 0b111 */
+ neg t1, a0
+ andi t1, t1, 0b111
+
+ sub a2, a2, t1
+
+ la t2, .Lduff_start
+ slli t3, t1, 3
+ sub t2, t2, t3
+ jr t2
+ lb t3, 6(a1)
+ sb t3, 6(a3)
+ lb t3, 5(a1)
+ sb t3, 5(a3)
+ lb t3, 4(a1)
+ sb t3, 4(a3)
+ lb t3, 3(a1)
+ sb t3, 3(a3)
+ lb t3, 2(a1)
+ sb t3, 2(a3)
+ lb t3, 1(a1)
+ sb t3, 1(a3)
+ lb t3, 0(a1)
+ sb t3, 0(a3)
+.Lduff_start:
+
+ add a1, a1, t1
+ add a3, a3, t1
+
+ beqz a2, .Lreturn
+
+ beqz t0, .Lmemcpy8
+
+ /*
+ * a4 - size_t right_shift
+ * a5 - size_t left_shift
+ * a6 - size_t whole (number of dword stores)
+ */
+
+ /* right_shift = (src % 0b111) * 8; */
+ andi a4, a1, 0b111
+ slli a4, a4, 3
+
+ /* left_shift = 64 - right_shift */
+ neg a5, a4
+
+ /* whole = len / 8 */
+ srli a6, a2, 3
+
+ /* len = len % 8 */
+ andi a2, a2, 0b111
+
+ /* t0 - uint64_t* ptr */
+
+ /* ptr = src & ~0b111 */
+ andi t0, a1, ~0b111
+
+ /* src += whole * 8 */
+ slli t1, a6, 3
+ add a1, a1, t1
+
+ /*
+ * t1 - uint64_t low
+ * t2 - uint64_t high
+ */
+
+ /* low = *ptr++ */
+ ld t1, (t0)
+ addi t0, t0, 8
+
+ /* low >>= right_shift */
+ srl t1, t1, a4
+
+ beqz a6, .Llmain_skip
+.Llmain:
+ /* high = *ptr++ */
+ ld t2, (t0)
+ addi t0, t0, 8
+
+ /* whole-- */
+ addi a6, a6, -1
+
+ /* temp = (high << left_shift) | low */
+ sll t3, t2, a5
+ or t3, t3, t1
+
+ /* low = high >> right_shift */
+ srl t1, t2, a4
+
+ /* *dst++ = temp */
+ sd t3, (a3)
+ addi a3, a3, 8
+
+ bnez a6, .Llmain
+
+.Llmain_skip:
+
+.Lend:
+ la t1, .Lduff_end
+ slli t2, a2, 3
+ sub t1, t1, t2
+ jr t1
+ lb t2, 6(a1)
+ sb t2, 6(a3)
+ lb t2, 5(a1)
+ sb t2, 5(a3)
+ lb t2, 4(a1)
+ sb t2, 4(a3)
+ lb t2, 3(a1)
+ sb t2, 3(a3)
+ lb t2, 2(a1)
+ sb t2, 2(a3)
+ lb t2, 1(a1)
+ sb t2, 1(a3)
+ lb t2, 0(a1)
+ sb t2, 0(a3)
+.Lduff_end:
+
+.Lreturn:
+ ret
+
+/* exectued when dst - src is multiple of 8
+ * a0 - void* dst
+ * a1 - const void* src
+ * a2 - size_t len
+ */
+.Lmemcpy8:
+
+ beqz a2, .Lreturn
+
+ slti t0, a2, 128
+ bnez t0, .Llmain8_64_skip
+
+ /* a4 - uint64_t* end_unroll */
+
+ /* end_unroll = dst + len / 64 * 64 */
+ andi t0, a2, ~0b111111
+ add a4, a3, t0
+
+ /* len = len % 64 */
+ andi a2, a2, 0b111111
+
+.Llmain8_64:
+ ld t0, 0(a1)
+ ld t1, 8(a1)
+ ld t2, 16(a1)
+ ld t3, 24(a1)
+ sd t0, 0(a3)
+ sd t1, 8(a3)
+ sd t2, 16(a3)
+ sd t3, 24(a3)
+ ld t0, 32(a1)
+ ld t1, 40(a1)
+ ld t2, 48(a1)
+ ld t3, 56(a1)
+ sd t0, 32(a3)
+ sd t1, 40(a3)
+ sd t2, 48(a3)
+ sd t3, 56(a3)
+ addi a3, a3, 64
+ addi a1, a1, 64
+ bne a3, a4, .Llmain8_64
+.Llmain8_64_skip:
+
+ beqz a2, .Lreturn
+
+ /* a4 - uint64_t* end_align */
+
+ /* end_align = (dst + len) & ~0b111 */
+ add a4, a3, a2
+ andi a4, a4, ~0b111
+
+ /* len = len % 8 */
+ andi a2, a2, 0b111
+
+ beq a3, a4, .Llmain8_skip
+.Llmain8:
+ ld t0, (a1)
+ sd t0, (a3)
+ addi a3, a3, 8
+ addi a1, a1, 8
+ bne a3, a4, .Llmain8
+.Llmain8_skip:
+
+ la t1, .Lduff_end
+ slli t2, a2, 3
+ sub t1, t1, t2
+ jr t1
+END(memcpy)

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