Merge branch 'wip' into work

1 files changed, 114 insertions, 0 deletions

diff --git a/host/lib/usrp/dsp_utils.hpp b/host/lib/usrp/dsp_utils.hpp
new file mode 100644
index 000000000..cfe5375f8
--- /dev/null
+++ b/host/lib/usrp/dsp_utils.hpp
@@ -0,0 +1,114 @@
+//
+// Copyright 2010 Ettus Research LLC
+//
+// 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+#ifndef INCLUDED_LIBUHD_USRP_DSP_UTILS_HPP
+#define INCLUDED_LIBUHD_USRP_DSP_UTILS_HPP
+
+#include <uhd/config.hpp>
+#include <uhd/utils/assert.hpp>
+#include <boost/cstdint.hpp>
+#include <boost/math/special_functions/round.hpp>
+
+namespace uhd{ namespace usrp{
+
+namespace dsp_type1{
+
+    template <class T> T ceil_log2(T num){
+        return std::ceil(std::log(num)/std::log(T(2)));
+    }
+
+    /*!
+     * Calculate the cordic word from the frequency and clock rate.
+     * The frequency will be set to the actual (possible) frequency.
+     *
+     * \param freq the requested frequency in Hz
+     * \param codec_rate the dsp codec rate in Hz
+     * \param the 32-bit cordic control word
+     */
+    static inline boost::uint32_t calc_cordic_word_and_update(
+        double &freq,
+        double codec_rate
+    ){
+        UHD_ASSERT_THROW(std::abs(freq) < codec_rate/2.0);
+        static const double scale_factor = std::pow(2.0, 32);
+
+        //calculate the freq register word
+        boost::uint32_t freq_word = boost::math::iround((freq / codec_rate) * scale_factor);
+
+        //update the actual frequency
+        freq = (double(freq_word) / scale_factor) * codec_rate;
+
+        return freq_word;
+    }
+
+    /*!
+     * Calculate the CIC filter word from the rate.
+     * Check if requested decim/interp rate is:
+     *      multiple of 4, enable two halfband filters
+     *      multiple of 2, enable one halfband filter
+     *      handle remainder in CIC
+     *
+     * \param rate the requested rate in Sps
+     * \return the 32-bit cic filter control word
+     */
+    template <typename dsp_rate_type>
+    static inline boost::uint32_t calc_cic_filter_word(dsp_rate_type rate){
+        int hb0 = 0, hb1 = 0;
+        if (not (rate & 0x1)){
+            hb0 = 1;
+            rate /= 2;
+        }
+        if (not (rate & 0x1)){
+            hb1 = 1;
+            rate /= 2;
+        }
+        return (hb1 << 9) | (hb0 << 8) | (rate & 0xff);
+    }
+
+    /*!
+     * Calculate the IQ scale factor word from I and Q components.
+     * \param i the I component of the scalar
+     * \param q the Q component of the scalar
+     * \return the 32-bit scale factor control word
+     */
+    static inline boost::uint32_t calc_iq_scale_word(
+        boost::int16_t i, boost::int16_t q
+    ){
+        return (boost::uint32_t(i) << 16) | (boost::uint32_t(q) << 0);
+    }
+
+    /*!
+     * Calculate the IQ scale factor word from the rate.
+     * \param rate the requested rate in Sps
+     * \return the 32-bit scale factor control word
+     */
+    template <typename dsp_rate_type>
+    static inline boost::uint32_t calc_iq_scale_word(dsp_rate_type rate){
+        // Calculate CIC interpolation (i.e., without halfband interpolators)
+        dsp_rate_type tmp_rate = calc_cic_filter_word(rate) & 0xff;
+
+        // Calculate closest multiplier constant to reverse gain absent scale multipliers
+        double rate_cubed = std::pow(double(tmp_rate), 3);
+        boost::int16_t scale = boost::math::iround((4096*std::pow(2, ceil_log2(rate_cubed)))/(1.65*rate_cubed));
+        return calc_iq_scale_word(scale, scale);
+    }
+
+} //namespace dsp_type1
+
+}} //namespace
+
+#endif /* INCLUDED_LIBUHD_USRP_DSP_UTILS_HPP */