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diff --git a/lib/libc/riscv/string/Makefile.inc b/lib/libc/riscv/string/Makefile.inc
new file mode 100644
--- /dev/null
+++ b/lib/libc/riscv/string/Makefile.inc
@@ -0,0 +1,2 @@
+MDSRCS+= \
+ memchr.S
diff --git a/lib/libc/riscv/string/memchr.S b/lib/libc/riscv/string/memchr.S
new file mode 100644
--- /dev/null
+++ b/lib/libc/riscv/string/memchr.S
@@ -0,0 +1,156 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Strahinja Stanisic <strajabot@FreeBSD.org>
+ */
+
+#include <machine/asm.h>
+
+/*
+ * a0 - const void* b
+ * a1 - int c;
+ * a2 - size_t len;
+ */
+ENTRY(memchr)
+ /*
+ * a0 - const void* b;
+ * a1 - char cccccccc[8];
+ * a2 - size_t len;
+ * a3 - size_t bound;
+ * a4 - char iter[8];
+ * a5 - const void* last
+ * a6 - size_t remaining
+ */
+
+ /* int to char */
+ andi a1, a1, 0xFF
+
+ /* strings where len < 8 handled here */
+ sltiu t0, a2, 8
+ beqz t0, .Lskip_lt_8
+.Llt_8:
+ beqz a2, .Lno_match
+ lb a4, (a0)
+ addi a2, a2, -1
+ addi a0, a0, 1
+ bne a1, a4, .Llt_8
+ addi a0, a0, -1
+ ret
+.Lskip_lt_8:
+
+ /* t0 = 0x0101010101010101 */
+ li t0, 0x01010101
+ slli t1, t0, 32
+ or t0, t0, t1
+
+ /* t1 = 0x8080808080808080 */
+ slli t1, t0, 7
+
+ /* spread char accross bytes */
+ mul a1, a1, t0
+
+ /* align_offset */
+ andi t2, a0, 0b111
+
+ /* align pointer */
+ andi a0, a0, ~0b111
+
+ /* used to check if c was found past the end of string */
+ li a3, 8
+
+ /* if pointer is aligned skip to loop */
+ beqz t2, .Lskip_start
+
+ /* len = len - (8-align_offset) */
+ addi t2, t2, -8
+ add a2, a2, t2
+
+ /* align first load */
+ ld a4, (a0)
+
+ xor a4, a4, a1
+
+ /* fill bytes before b with non-zero */
+ slli t2, t2, 3
+ neg t2, t2
+ srl t2, t0, t2
+ or a4, a4, t2
+
+ /* has_zero */
+ not t2, a4
+ sub a4, a4, t0
+ and a4, a4, t2
+ and a4, a4, t1
+
+ bnez a4, .Lfind_zero
+
+ /* first iteration exit */
+ addi a0, a0, 8
+
+.Lskip_start:
+ add t2, a0, a2
+ andi a5, t2, ~0b111
+
+ /* remaining bytes to check after the loop */
+ andi a6, t2, 0b111
+
+ /* while (b != last) */
+ beq a0, a5, .Lskip_loop
+.Lloop:
+ ld a4, (a0)
+ xor a4, a4, a1
+
+ /* has_zero */
+ not t2, a4
+ sub a4, a4, t0
+ and a4, a4, t2
+ and a4, a4, t1
+
+ bnez a4, .Lfind_zero
+
+ addi a0, a0, 8
+ bne a0, a5, .Lloop
+
+.Lskip_loop:
+ /* ignore bytes past remaining in cccccccc */
+ mv a3, a6
+
+ /* 0 bytes remaining to check */
+ beqz a3, .Lno_match
+
+ ld a4, (a0)
+ xor a4, a4, a1
+
+ /* has_zero */
+ not t2, a4
+ sub a4, a4, t0
+ and a4, a4, t2
+ and a4, a4, t1
+
+ bnez a4, .Lfind_zero
+
+.Lno_match:
+ li a0, 0
+ ret
+
+.Lfind_zero:
+ /* isolate lowest set bit */
+ neg t0, a4
+ and a4, a4, t0
+
+ li t0, 0x0001020304050607
+ srli a4, a4, 7
+
+ /* lowest set bit is 2^(8*k)
+ * multiplying by it shifts the idx array in t0 by k bytes to the left */
+ mul a4, a4, t0
+
+ /* highest byte contains idx of first zero */
+ srli a4, a4, 56
+
+ /* bounds check */
+ bgeu a4, a3, .Lno_match
+
+ add a0, a0, a4
+ ret
+END(memchr)
diff --git a/share/man/man7/simd.7 b/share/man/man7/simd.7
--- a/share/man/man7/simd.7
+++ b/share/man/man7/simd.7
@@ -50,7 +50,7 @@
.Pp
Enhanced functions are present for the following architectures:
.Bl -column FUNCTION_________ aarch64_ arm_ amd64_ i386_ ppc64_ -offset indent
-.It Em FUNCTION Ta Em AARCH64 Ta Em ARM Ta Em AMD64 Ta Em I386 Ta Em PPC64
+.It Em FUNCTION Ta Em AARCH64 Ta Em ARM Ta Em AMD64 Ta Em I386 Ta Em PPC64 Ta Em RISC-V
.It bcmp Ta Ta Ta S1 Ta S
.It bcopy Ta Ta S Ta S Ta S Ta SV
.It bzero Ta Ta S Ta S Ta S
@@ -58,7 +58,7 @@
.It index Ta A Ta Ta S1
.It ldiv Ta Ta Ta S Ta S
.It lldiv Ta Ta Ta S
-.It memchr Ta A Ta Ta S1
+.It memchr Ta A Ta Ta S1 Ta Ta Ta S
.It memcmp Ta A Ta S Ta S1 Ta S
.It memccpy Ta Ta Ta S1
.It memcpy Ta S Ta S Ta S Ta S Ta SV

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