Add multiply & divide implementations for 128-bit unsigned integers.

Author: martinling

firmware/common/u128.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2026 Great Scott Gadgets <info@greatscottgadgets.com>
+ *
+ * This file is part of HackRF.
+ *
+ * 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, or (at your option)
+ * 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "u128.h"
+
+/* From https://stackoverflow.com/a/58381061 */
+
+u128 u128_multiply(uint64_t lhs, uint64_t rhs)
+{
+	uint64_t lo_lo = (lhs & 0xFFFFFFFF) * (rhs & 0xFFFFFFFF);
+	uint64_t hi_lo = (lhs >> 32) * (rhs & 0xFFFFFFFF);
+	uint64_t lo_hi = (lhs & 0xFFFFFFFF) * (rhs >> 32);
+	uint64_t hi_hi = (lhs >> 32) * (rhs >> 32);
+	uint64_t cross = ((lo_lo >> 32) + (hi_lo & 0xFFFFFFFF) + lo_hi);
+	return (u128){
+		.hi = ((hi_lo >> 32) + (cross >> 32) + hi_hi),
+		.lo = ((cross << 32) | (lo_lo & 0xFFFFFFFF)),
+	};
+}
+
+/* From https://stackoverflow.com/a/70052545 */
+
+/* clang-format off */
+
+#define SUBCcc(a,b,cy,t0,t1,t2) \
+  (t0=(b)+cy, t1=(a), cy=t0<cy, t2=t1<t0, cy=cy+t2, t1-t0)
+
+#define SUBcc(a,b,cy,t0,t1) \
+  (t0=(b), t1=(a), cy=t1<t0, t1-t0)
+
+#define SUBC(a,b,cy,t0,t1) \
+  (t0=(b)+cy, t1=(a), t1-t0)
+
+#define ADDCcc(a,b,cy,t0,t1) \
+  (t0=(b)+cy, t1=(a), cy=t0<cy, t0=t0+t1, t1=t0<t1, cy=cy+t1, t0=t0)
+
+#define ADDcc(a,b,cy,t0,t1) \
+  (t0=(b), t1=(a), t0=t0+t1, cy=t0<t1, t0=t0)
+
+#define ADDC(a,b,cy,t0,t1) \
+  (t0=(b)+cy, t1=(a), t0+t1)
+
+/* clang-format on */
+
+u128 u128_divide(u128 dvnd, u128 dvsr)
+{
+	u128 quot, rem, tmp;
+	uint64_t cy, t0, t1, t2;
+
+	quot.hi = dvnd.hi;
+	quot.lo = dvnd.lo;
+	rem.hi = 0;
+	rem.lo = 0;
+
+	for (int i = 0; i < 128; i++) {
+		quot.lo = ADDcc(quot.lo, quot.lo, cy, t0, t1);
+		quot.hi = ADDCcc(quot.hi, quot.hi, cy, t0, t1);
+		rem.lo = ADDCcc(rem.lo, rem.lo, cy, t0, t1);
+		rem.hi = ADDC(rem.hi, rem.hi, cy, t0, t1);
+		tmp.lo = SUBcc(rem.lo, dvsr.lo, cy, t0, t1);
+		tmp.hi = SUBCcc(rem.hi, dvsr.hi, cy, t0, t1, t2);
+		if (!cy) { // remainder >= divisor
+			rem.lo = tmp.lo;
+			rem.hi = tmp.hi;
+			quot.lo |= 1;
+		}
+	}
+
+	return quot;
+}

firmware/common/u128.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2026 Great Scott Gadgets <info@greatscottgadgets.com>
+ *
+ * This file is part of HackRF.
+ *
+ * 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, or (at your option)
+ * 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+typedef struct {
+	uint64_t hi;
+	uint64_t lo;
+} u128;
+
+u128 u128_multiply(uint64_t a, uint64_t b);
+u128 u128_divide(u128 dvnd, u128 dvsr);

firmware/hackrf-common.cmake

@@ -203,6 +203,7 @@ macro(DeclareTargets)
 		${PATH_HACKRF_FIRMWARE_COMMON}/adc.c
 		${PATH_HACKRF_FIRMWARE_COMMON}/da7219.c
 		${PATH_HACKRF_FIRMWARE_COMMON}/max283x.c
+		${PATH_HACKRF_FIRMWARE_COMMON}/u128.c
 	)
 
 	if(BOARD STREQUAL "RAD1O")