diff --git a/dsp.h b/dsp.h
new file mode 100644
index 0000000..a257652
--- /dev/null
+++ b/dsp.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2019-2020, Dmitry (DiSlord) dislordlive@gmail.com
+ * All rights reserved.
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * The software 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+// Cortex M4 DSP instructions assembly
+
+// __smlabb inserts a SMLABB instruction. __smlabb returns the equivalent of
+//  int32_t res = x[0] * y[0] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits. This operation sets the Q flag if overflow occurs on the addition.
+__attribute__((always_inline)) __STATIC_INLINE int32_t __smlabb(int32_t x, int32_t y, int32_t acc)
+{
+  register int32_t r;
+  __ASM volatile ("smlabb %[r], %[x], %[y], %[a]"
+   : [r] "=r" (r) : [x] "r" (x), [y] "r" (y), [a] "r" (acc) : );
+  return r;
+}
+
+// __smlabt inserts a SMLABT instruction. __smlabt returns the equivalent of
+//  int32_t res = x[0] * y[1] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits. This operation sets the Q flag if overflow occurs on the addition.
+__attribute__((always_inline)) __STATIC_INLINE int32_t __smlabt(int32_t x, int32_t y, int32_t acc)
+{
+  register int32_t r;
+  __ASM volatile ("smlabt %[r], %[x], %[y], %[a]"
+   : [r] "=r" (r) : [x] "r" (x), [y] "r" (y), [a] "r" (acc) : );
+  return r;
+}
+
+// __smlatb inserts a SMLATB instruction. __smlatb returns the equivalent of
+//  int32_t res = x[1] * y[0] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits. This operation sets the Q flag if overflow occurs on the addition.
+__attribute__((always_inline)) __STATIC_INLINE int32_t __smlatb(int32_t x, int32_t y, int32_t acc)
+{
+  register int32_t r;
+  __ASM volatile ("smlatb %[r], %[x], %[y], %[a]"
+   : [r] "=r" (r) : [x] "r" (x), [y] "r" (y), [a] "r" (acc) : );
+  return r;
+}
+
+// __smlatt inserts a SMLATT instruction. __smlatt returns the equivalent of
+//  int32_t res = x[1] * y[1] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits. This operation sets the Q flag if overflow occurs on the addition.
+__attribute__((always_inline)) __STATIC_INLINE int32_t __smlatt(int32_t x, int32_t y, int32_t acc)
+{
+  register int32_t r;
+  __ASM volatile ("smlatt %[r], %[x], %[y], %[a]"
+   : [r] "=r" (r) : [x] "r" (x), [y] "r" (y), [a] "r" (acc) : );
+  return r;
+}
+
+// __smlalbb inserts a SMLALBB instruction. __smlalbb returns the equivalent of
+//  int64_t res = x[0] * y[0] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits.
+__attribute__((always_inline)) __STATIC_INLINE int64_t __smlalbb(int64_t acc, int32_t x, int32_t y)
+{
+  register union {
+    struct { uint32_t lo; uint32_t hi; } s_rep;
+    int64_t i_rep;
+  } r;
+  r.i_rep = acc;
+  __ASM volatile ("smlalbb %[r_lo], %[r_hi], %[x], %[y]"
+   : [r_lo] "+r" (r.s_rep.lo), [r_hi] "+r" (r.s_rep.hi)
+   : [x] "r" (x), [y] "r" (y) : );
+  return r.i_rep;
+}
+
+// __smlalbt inserts a SMLALBT instruction. __smlalbt returns the equivalent of
+//  int64_t res = x[0] * y[1] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits.
+__attribute__((always_inline)) __STATIC_INLINE int64_t __smlalbt(int64_t acc, int32_t x, int32_t y)
+{
+  register union {
+    struct { uint32_t lo; uint32_t hi; } s_rep;
+    int64_t i_rep;
+  } r;
+  r.i_rep = acc;
+  __ASM volatile ("smlalbt %[r_lo], %[r_hi], %[x], %[y]"
+   : [r_lo] "+r" (r.s_rep.lo), [r_hi] "+r" (r.s_rep.hi)
+   : [x] "r" (x), [y] "r" (y) : );
+  return r.i_rep;
+}
+
+// __smlaltb inserts a SMLALTB instruction. __smlaltb returns the equivalent of
+//  int64_t res = x[1] * y[0] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits.
+__attribute__((always_inline)) __STATIC_INLINE int64_t __smlaltb(int64_t acc, int32_t x, int32_t y)
+{
+  register union {
+    struct { uint32_t lo; uint32_t hi; } s_rep;
+    int64_t i_rep;
+  } r;
+  r.i_rep = acc;
+  __ASM volatile ("smlaltb %[r_lo], %[r_hi], %[x], %[y]"
+   : [r_lo] "+r" (r.s_rep.lo), [r_hi] "+r" (r.s_rep.hi)
+   : [x] "r" (x), [y] "r" (y) : );
+  return r.i_rep;
+}
+
+// __smlaltt inserts a SMLALTT instruction. __smlaltt returns the equivalent of
+//  int64_t res = x[1] * y[1] + acc
+//  where [0] is the lower 16 bits and [1] is the upper 16 bits.
+static inline int64_t __smlaltt(int64_t acc, int32_t x, int32_t y)
+{
+  register union {
+    struct { uint32_t lo; uint32_t hi; } s_rep;
+    int64_t i_rep;
+  } r;
+  r.i_rep = acc;
+  __ASM volatile ("smlaltt %[r_lo], %[r_hi], %[x], %[y]"
+    : [r_lo] "+r" (r.s_rep.lo), [r_hi] "+r" (r.s_rep.hi)
+    : [x] "r" (x), [y] "r" (y) : );
+  return r.i_rep;
+}
diff --git a/rtc.c b/rtc.c
index 13e33dc..9bac4d9 100644
--- a/rtc.c
+++ b/rtc.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2020, Dmitry (DiSlord) dislordlive@gmail.com
+ * Copyright (c) 2019-2020, Dmitry (DiSlord) dislordlive@gmail.com
  * All rights reserved.
  *
  * This is free software; you can redistribute it and/or modify