1 files changed, 70 insertions, 0 deletions
diff --git a/src/arch/riscv/core/riscv_strings.S b/src/arch/riscv/core/riscv_strings.S
new file mode 100644
index 000000000..eb1b397b9
--- /dev/null
+++ b/src/arch/riscv/core/riscv_strings.S
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2024 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+	FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
+
+/** @file
+ *
+ * Byte swapping
+ *
+ */
+
+	.section ".note.GNU-stack", "", @progbits
+	.text
+
+/**
+ * Find first (i.e. least significant) set bit
+ *
+ * @v value		Value
+ * @ret lsb		Least significant bit set in value (LSB=1), or zero
+ */
+	.section ".text.riscv_ffs"
+	.globl	riscv_ffs
+riscv_ffs:
+	beqz	a0, 2f
+	mv	t0, a0
+	li	a0, ( __riscv_xlen + 1 )
+1:	slli	t0, t0, 1
+	addi	a0, a0, -1
+	bnez	t0, 1b
+2:	ret
+	.size	riscv_ffs, . - riscv_ffs
+
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v value		Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
+	.section ".text.riscv_fls"
+	.globl	riscv_fls
+riscv_fls:
+	beqz	a0, 2f
+	mv	t0, a0
+	li	a0, __riscv_xlen
+	bltz	t0, 2f
+1:	slli	t0, t0, 1
+	addi	a0, a0, -1
+	bgez	t0, 1b
+2:	ret
+	.size	riscv_fls, . - riscv_fls