Missing signal opts

signal/micro/kernels/fft_test.cc

@@ -275,7 +275,7 @@ TF_LITE_MICRO_TEST(RfftTestSize512Int16) {
       tflite::tflm_signal::Register_RFFT_INT16();
 // See (b/287518815) for why this is needed.
 #if defined(HIFI3) || defined(HIFI4) || defined(HIFI5)
-  int tolerance = 9;
+  int tolerance = 16;
 #else   // defined(HIFI3) || defined(HIFI4) || defined(HIFI5)
   int tolerance = 3;
 #endif  // defined(HIFI3) || defined(HIFI4) || defined(HIFI5)

signal/micro/kernels/hexagon/hexagon_square_root.S

@@ -0,0 +1,110 @@
+/* Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+.section        .note.GNU-stack,"",@progbits
+
+// SignalHexagonSqrt32
+//      input:  R0 unsigned 32-bit
+//      output: R0 unsigned 32-bit
+//
+// The assembly routine below implements the following:
+//
+//   uint16_t Sqrt32(uint32_t num) {
+//     uint32_t res = 0;
+//     uint32_t bit = ((int32_t)1) << 30U;
+//     while (bit > num)
+//       bit >>= 2;
+//     while (bit != 0) {
+//       if (num >= res + bit) {
+//         num -= res + bit;
+//         res = (res >> 1U) + bit;
+//       } else {
+//         res >>= 1U;
+//       }
+//       bit >>= 2U;
+//     }
+//     // Do rounding
+//     if (num > res && num != 0xFFFF)
+//       ++res;
+//     return res;
+//   }
+
+.text
+.p2align 2
+.p2align 4,,15
+.globl   SignalHexagonSqrt32
+.type    SignalHexagonSqrt32, @function
+
+                                // Register mnemonics
+#define num R0                  // input - as in loop above
+#define res R1                  // as in loop aboe
+#define bit R2                  // as in loop above
+#define temp R3                 // the quantity bit + res
+#define zcount R4               // leading zeroes
+#define res_shift R5            // the quantity res >> 1
+#define bit_shift R6            // the quantity bit >> 2
+
+SignalHexagonSqrt32:
+                // Set bit to the largest even-power of two
+                // that is less than or equal to the input
+        {
+                res = #0                                // return value
+                bit = ##1073741824                      // 2^30
+                zcount = cl0(num)                       // count leading zeroes
+        }
+                zcount = clrbit(zcount, #0)             // even power of 2
+        {
+                bit = lsr(bit, zcount)                  // 2^30 right shifted
+                if (cmp.eq(bit.new, #0)) jump:nt .done  // return if bit == 0
+        }
+.falign
+.loop:
+        {
+                // Calculate quantities to be used in the conditional below
+                temp = add(bit, res)
+                res_shift = lsr(res, #1)
+                bit_shift = lsr(bit, #2)
+        }
+        {
+                // Conditionally assign to num and res
+                p0 = cmp.ltu(temp, num)
+                if (p0.new) num = sub(num, temp)
+                if (p0.new) res = add(res_shift, bit)
+                if (!p0.new) res = res_shift
+        }
+        {
+                // Advance bit >> 2 and exit loop if done
+                bit = bit_shift
+                if (cmp.gt(bit.new, #0)) jump:t .loop
+        }
+.falign
+.done:
+                // if (num > res && res != 0xffff) {
+                //   ++res
+                // }
+                // return res in num (R0)
+        {
+                temp = ##65535
+        }
+        {
+                p0 = cmp.gt(num, res)
+                p0 = !cmp.eq(res, temp)
+                if (p0.new) num = add(res, #1)
+                if (!p0.new) num = res
+        }
+        {
+                jumpr r31
+        }
+.size   SignalHexagonSqrt32, .-SignalHexagonSqrt32

signal/micro/kernels/hexagon/rfft_int16.cc

@@ -0,0 +1,187 @@
+/* Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "signal/src/msb.h"
+#include "signal/src/rfft.h"
+
+// Do not reorder these headers.  "typedef.h" must appear before rfft.h
+#include "typedef.h"
+extern "C" {
+#include "rfft.h"
+}
+
+namespace tflm_signal {
+
+// TODO(b/467010877) The twiddle tables should come from the tflite file
+// This array includes the first 3*512/4=384 elements in the twiddle table in:
+// HEXAGON_Tools/<TOOL_VERSION>/Examples/libcore/SigProc/cxFFT_IFFT/include
+const uint16_t twiddles[] __attribute__((aligned(8))) = {
+    0x7fff, 0x0000, 0x0000, 0x8000, 0x0000, 0x8000, 0x0000, 0x8000, 0xa57e,
+    0xa57e, 0xa57e, 0x5a82, 0x5a82, 0xa57e, 0xcf05, 0x89bf, 0x89bf, 0xcf05,
+    0xa57e, 0xa57e, 0x89bf, 0xcf05, 0x30fc, 0x7642, 0x7642, 0xcf05, 0xe708,
+    0x8276, 0xb8e4, 0x9593, 0xcf05, 0x89bf, 0x9593, 0xb8e4, 0xe708, 0x7d8a,
+    0x30fc, 0x89bf, 0xb8e4, 0x9593, 0x8276, 0x18f9, 0x89bf, 0xcf05, 0x8276,
+    0xe708, 0x6a6e, 0x471d, 0x7d8a, 0xe708, 0xf375, 0x809e, 0xdad8, 0x8583,
+    0xe708, 0x8276, 0x9d0e, 0xaecd, 0xc3aa, 0x70e3, 0x471d, 0x9593, 0xc3aa,
+    0x8f1e, 0x809e, 0xf375, 0x9593, 0xb8e4, 0x8583, 0xdad8, 0x5134, 0x62f2,
+    0x6a6e, 0xb8e4, 0xdad8, 0x8583, 0x9d0e, 0xaecd, 0xb8e4, 0x9593, 0x8f1e,
+    0xc3aa, 0x0c8c, 0x7f62, 0x18f9, 0x8276, 0xaecd, 0x9d0e, 0x8f1e, 0x3c57,
+    0x8276, 0xe708, 0x809e, 0xf375, 0x7a7d, 0x2528, 0x7f62, 0xf375, 0xf9b9,
+    0x8028, 0xed38, 0x8163, 0xf375, 0x809e, 0xa129, 0xaa0b, 0xb3c1, 0x66d0,
+    0x5134, 0x9d0e, 0xc946, 0x8c4b, 0x83d7, 0xe0e7, 0x9d0e, 0xaecd, 0x877c,
+    0xd4e1, 0x41ce, 0x6dca, 0x70e3, 0xc3aa, 0xe0e7, 0x83d7, 0xaa0b, 0xa129,
+    0xc3aa, 0x8f1e, 0x9236, 0xbe32, 0xf9b9, 0x7fd9, 0x2528, 0x8583, 0xb3c1,
+    0x9931, 0x877c, 0x2b1f, 0x8583, 0xdad8, 0x8163, 0xed38, 0x73b6, 0x36ba,
+    0x7a7d, 0xdad8, 0xed38, 0x8163, 0xc946, 0x8c4b, 0xdad8, 0x8583, 0x9931,
+    0xb3c1, 0xd4e1, 0x7885, 0x3c57, 0x8f1e, 0xbe32, 0x9236, 0x8028, 0x0648,
+    0x8f1e, 0xc3aa, 0x83d7, 0xe0e7, 0x5ed7, 0x55f6, 0x62f2, 0xaecd, 0xd4e1,
+    0x877c, 0x9236, 0xbe32, 0xaecd, 0x9d0e, 0x8c4b, 0xc946, 0x1f1a, 0x7c2a,
+    0x0c8c, 0x809e, 0xaa0b, 0xa129, 0x9931, 0x4c40, 0x809e, 0xf375, 0x8028,
+    0xf9b9, 0x7e9d, 0x12c8, 0x7fd9, 0xf9b9, 0xfcdc, 0x800a, 0xf696, 0x8059,
+    0xf9b9, 0x8028, 0xa34c, 0xa7be, 0xac65, 0x60ec, 0x55f6, 0xa129, 0xcc22,
+    0x8afc, 0x8676, 0xd7da, 0xa129, 0xaa0b, 0x8894, 0xd1ef, 0x398d, 0x7255,
+    0x73b6, 0xc946, 0xe3f5, 0x831d, 0xb141, 0x9b18, 0xc946, 0x8c4b, 0x93dc,
+    0xbb86, 0xf055, 0x7f0a, 0x2b1f, 0x877c, 0xb64c, 0x975a, 0x84a3, 0x2224,
+    0x877c, 0xd4e1, 0x81e3, 0xea1e, 0x6f5f, 0x3f17, 0x7c2a, 0xe0e7, 0xf055,
+    0x80f7, 0xd1ef, 0x8894, 0xe0e7, 0x83d7, 0x9b18, 0xb141, 0xcc22, 0x7505,
+    0x41ce, 0x9236, 0xc0e9, 0x90a1, 0x800a, 0xfcdc, 0x9236, 0xbe32, 0x84a3,
+    0xdddd, 0x5843, 0x5cb4, 0x66d0, 0xb3c1, 0xd7da, 0x8676, 0x975a, 0xb64c,
+    0xb3c1, 0x9931, 0x8dab, 0xc674, 0x15e2, 0x7e1e, 0x12c8, 0x8163, 0xac65,
+    0x9f14, 0x93dc, 0x447b, 0x8163, 0xed38, 0x8059, 0xf696, 0x7ce4, 0x1c0c,
+    0x7e9d, 0xed38, 0xf696, 0x8059, 0xe3f5, 0x831d, 0xed38, 0x8163, 0x9f14,
+    0xac65, 0xbb86, 0x6c24, 0x4c40, 0x9931, 0xc674, 0x8dab, 0x81e3, 0xea1e,
+    0x9931, 0xb3c1, 0x8676, 0xd7da, 0x49b4, 0x68a7, 0x6dca, 0xbe32, 0xdddd,
+    0x84a3, 0xa34c, 0xa7be, 0xbe32, 0x9236, 0x90a1, 0xc0e9, 0x0324, 0x7ff6,
+    0x1f1a, 0x83d7, 0xb141, 0x9b18, 0x8afc, 0x33df, 0x83d7, 0xe0e7, 0x80f7,
+    0xf055, 0x776c, 0x2e11, 0x7885, 0xd4e1, 0xea1e, 0x81e3, 0xc0e9, 0x90a1,
+    0xd4e1, 0x877c, 0x975a, 0xb64c, 0xdddd, 0x7b5d, 0x36ba, 0x8c4b, 0xbb86,
+    0x93dc, 0x80f7, 0x0fab, 0x8c4b, 0xc946, 0x831d, 0xe3f5, 0x64e9, 0x4ec0,
+    0x5ed7, 0xaa0b, 0xd1ef, 0x8894, 0x8dab, 0xc674, 0xaa0b, 0xa129, 0x8afc,
+    0xcc22, 0x2827, 0x798a, 0x0648, 0x8028, 0xa7be, 0xa34c, 0x9f14, 0x539b,
+    0x8028, 0xf9b9, 0x800a, 0xfcdc, 0x7fa7, 0x096b, 0x7ff6, 0xfcdc, 0xfe6e,
+    0x8003, 0xfb4a, 0x8017, 0xfcdc, 0x800a, 0xa463, 0xa69c, 0xa8e3, 0x5dc8,
+    0x5843, 0xa34c, 0xcd92, 0x8a5b, 0x8806, 0xd368, 0xa34c, 0xa7be, 0x8927,
+    0xd079, 0x354e, 0x7460, 0x7505, 0xcc22, 0xe57e, 0x82c7, 0xb505, 0x9843,
+    0xcc22, 0x8afc, 0x94b6, 0xba33, 0xebab, 0x7e60, 0x2e11, 0x8894, 0xb797,
+    0x9674, 0x8377, 0x1d93, 0x8894, 0xd1ef, 0x822a, 0xe893, 0x6cf9, 0x4326,
+    0x7ce4, 0xe3f5, 0xf1e5, 0x80c8, 0xd65d, 0x86f7, 0xe3f5, 0x831d, 0x9c11,
+    0xb005, 0xc7dc, 0x7308, 0x447b, 0x93dc, 0xc248, 0x8fdd, 0x803e, 0xf827,
+    0x93dc, 0xbb86, 0x8511, 0xdc5a, 0x54ca, 0x5fe4, 0x68a7, 0xb64c, 0xd958,
+    0x85fb, 0x9a23, 0xb27f, 0xb64c, 0x975a, 0x8e62, 0xc50e, 0x113a, 0x7ed6,
+    0x15e2, 0x81e3, 0xad97, 0x9e0f, 0x916a, 0x4074, 0x81e3, 0xea1e, 0x8079,
+    0xf505, 0x7bc6, 0x209f, 0x7f0a, 0xf055, 0xf827, 0x803e, 0xe893, 0x822a,
+    0xf055, 0x80f7, 0xa01d, 0xab36, 0xb797, 0x698c, 0x4ec0, 0x9b18, 0xc7dc,
+    0x8cf9, 0x82c7, 0xe57e, 0x9b18, 0xb141, 0x86f7, 0xd65d, 0x45cd, 0x6b4b,
+    0x6f5f, 0xc0e9, 0xdf61, 0x843b, 0xa69c, 0xa463, 0xc0e9, 0x90a1, 0x916a,
+    0xbf8d, 0xfe6e, 0x7ffe, 0x2224, 0x84a3, 0xb27f, 0x9a23, 0x8927, 0x2f87,
+    0x84a3, 0xdddd, 0x812b, 0xeec7, 0x75a6, 0x326e, 0x798a, 0xd7da, 0xebab,
+    0x81a1, 0xc50e, 0x8e62, 0xd7da, 0x8676, 0x9843, 0xb505, 0xd958, 0x7a06,
+    0x398d, 0x8dab, 0xbcdb, 0x9307, 0x8079, 0x0afb, 0x8dab, 0xc674, 0x8377,
+    0xe26d, 0x61f1, 0x5269, 0x60ec, 0xac65, 0xd368, 0x8806, 0x8fdd, 0xc248,
+    0xac65, 0x9f14, 0x8ba1, 0xcab3, 0x23a7, 0x7aef, 0x096b, 0x8059, 0xa8e3,
+    0xa239, 0x9c11, 0x4ffb, 0x8059, 0xf696, 0x8017, 0xfb4a, 0x7f38, 0x0e1c,
+    0x7fa7, 0xf696, 0xfb4a, 0x8017, 0xf1e5, 0x80c8, 0xf696, 0x8059, 0xa239,
+    0xa8e3, 0xb005, 0x63ef, 0x539b, 0x9f14, 0xcab3, 0x8ba1, 0x8511, 0xdc5a,
+    0x9f14, 0xac65, 0x8806, 0xd368, 0x3db8, 0x7023, 0x7255, 0xc674, 0xe26d,
+    0x8377, 0xad97, 0x9e0f, 0xc674, 0x8dab, 0x9307, 0xbcdb, 0xf505, 0x7f87,
+    0x2827, 0x8676, 0xb505, 0x9843, 0x85fb, 0x26a8, 0x8676, 0xd7da, 0x81a1,
+    0xebab, 0x719e, 0x3af3, 0x7b5d, 0xdddd, 0xeec7, 0x812b, 0xcd92, 0x8a5b,
+    0xdddd, 0x84a3, 0x9a23, 0xb27f, 0xd079, 0x76d9, 0x3f17, 0x90a1, 0xbf8d,
+    0x916a, 0x8003, 0x0192, 0x90a1, 0xc0e9, 0x843b, 0xdf61, 0x5b9d, 0x5964,
+    0x64e9, 0xb141, 0xd65d, 0x86f7, 0x94b6, 0xba33, 0xb141, 0x9b18, 0x8cf9,
+    0xc7dc, 0x1a83, 0x7d3a, 0x0fab, 0x80f7, 0xab36, 0xa01d, 0x9674, 0x486a,
+    0x80f7, 0xf055, 0x803e, 0xf827, 0x7dd6, 0x176e, 0x7e1e, 0xea1e, 0xf505,
+    0x8079, 0xdf61, 0x843b, 0xea1e, 0x81e3, 0x9e0f, 0xad97, 0xbf8d, 0x6e97,
+    0x49b4, 0x975a, 0xc50e, 0x8e62, 0x812b, 0xeec7, 0x975a, 0xb64c, 0x85fb,
+    0xd958, 0x4d81, 0x65de, 0x6c24, 0xbb86, 0xdc5a, 0x8511, 0xa01d, 0xab36,
+    0xbb86, 0x93dc, 0x8fdd, 0xc248, 0x07d9, 0x7fc2, 0x1c0c, 0x831d, 0xb005,
+    0x9c11, 0x8cf9, 0x3825, 0x831d, 0xe3f5, 0x80c8, 0xf1e5, 0x790a, 0x29a4,
+    0x776c, 0xd1ef, 0xe893, 0x822a, 0xbcdb, 0x9307, 0xd1ef, 0x8894, 0x9674,
+    0xb797, 0xe26d, 0x7c89, 0x33df, 0x8afc, 0xba33, 0x94b6, 0x81a1, 0x1455,
+    0x8afc, 0xcc22, 0x82c7, 0xe57e, 0x67bd, 0x4afb, 0x5cb4, 0xa7be, 0xd079,
+    0x8927, 0x8ba1, 0xcab3, 0xa7be, 0xa34c, 0x8a5b, 0xcd92, 0x2c99, 0x77fb,
+    0x0324, 0x800a, 0xa69c, 0xa463, 0xa239, 0x571e, 0x800a, 0xfcdc, 0x8003,
+    0xfe6e, 0x7fea, 0x04b6};
+
+// Twiddle factors used for the last stage of N-point real FFT
+// generated as j*W^k, k=1, 2, ... N/4
+// That's 128 complex int16_t elements
+// Or 256 real int16_t elements
+const uint16_t rtwiddles[] __attribute__((aligned(8))) = {
+    0x0192, 0x7ffe, 0x0324, 0x7ff6, 0x04b6, 0x7fea, 0x0648, 0x7fd9, 0x07d9,
+    0x7fc2, 0x096b, 0x7fa7, 0x0afb, 0x7f87, 0x0c8c, 0x7f62, 0x0e1c, 0x7f38,
+    0x0fab, 0x7f0a, 0x113a, 0x7ed6, 0x12c8, 0x7e9d, 0x1455, 0x7e60, 0x15e2,
+    0x7e1e, 0x176e, 0x7dd6, 0x18f9, 0x7d8a, 0x1a83, 0x7d3a, 0x1c0c, 0x7ce4,
+    0x1d93, 0x7c89, 0x1f1a, 0x7c2a, 0x209f, 0x7bc6, 0x2224, 0x7b5d, 0x23a7,
+    0x7aef, 0x2528, 0x7a7d, 0x26a8, 0x7a06, 0x2827, 0x798a, 0x29a4, 0x790a,
+    0x2b1f, 0x7885, 0x2c99, 0x77fb, 0x2e11, 0x776c, 0x2f87, 0x76d9, 0x30fc,
+    0x7642, 0x326e, 0x75a6, 0x33df, 0x7505, 0x354e, 0x7460, 0x36ba, 0x73b6,
+    0x3825, 0x7308, 0x398d, 0x7255, 0x3af3, 0x719e, 0x3c57, 0x70e3, 0x3db8,
+    0x7023, 0x3f17, 0x6f5f, 0x4074, 0x6e97, 0x41ce, 0x6dca, 0x4326, 0x6cf9,
+    0x447b, 0x6c24, 0x45cd, 0x6b4b, 0x471d, 0x6a6e, 0x486a, 0x698c, 0x49b4,
+    0x68a7, 0x4afb, 0x67bd, 0x4c40, 0x66d0, 0x4d81, 0x65de, 0x4ec0, 0x64e9,
+    0x4ffb, 0x63ef, 0x5134, 0x62f2, 0x5269, 0x61f1, 0x539b, 0x60ec, 0x54ca,
+    0x5fe4, 0x55f6, 0x5ed7, 0x571e, 0x5dc8, 0x5843, 0x5cb4, 0x5964, 0x5b9d,
+    0x5a82, 0x5a82, 0x5b9d, 0x5964, 0x5cb4, 0x5843, 0x5dc8, 0x571e, 0x5ed7,
+    0x55f6, 0x5fe4, 0x54ca, 0x60ec, 0x539b, 0x61f1, 0x5269, 0x62f2, 0x5134,
+    0x63ef, 0x4ffb, 0x64e9, 0x4ec0, 0x65de, 0x4d81, 0x66d0, 0x4c40, 0x67bd,
+    0x4afb, 0x68a7, 0x49b4, 0x698c, 0x486a, 0x6a6e, 0x471d, 0x6b4b, 0x45cd,
+    0x6c24, 0x447b, 0x6cf9, 0x4326, 0x6dca, 0x41ce, 0x6e97, 0x4074, 0x6f5f,
+    0x3f17, 0x7023, 0x3db8, 0x70e3, 0x3c57, 0x719e, 0x3af3, 0x7255, 0x398d,
+    0x7308, 0x3825, 0x73b6, 0x36ba, 0x7460, 0x354e, 0x7505, 0x33df, 0x75a6,
+    0x326e, 0x7642, 0x30fc, 0x76d9, 0x2f87, 0x776c, 0x2e11, 0x77fb, 0x2c99,
+    0x7885, 0x2b1f, 0x790a, 0x29a4, 0x798a, 0x2827, 0x7a06, 0x26a8, 0x7a7d,
+    0x2528, 0x7aef, 0x23a7, 0x7b5d, 0x2224, 0x7bc6, 0x209f, 0x7c2a, 0x1f1a,
+    0x7c89, 0x1d93, 0x7ce4, 0x1c0c, 0x7d3a, 0x1a83, 0x7d8a, 0x18f9, 0x7dd6,
+    0x176e, 0x7e1e, 0x15e2, 0x7e60, 0x1455, 0x7e9d, 0x12c8, 0x7ed6, 0x113a,
+    0x7f0a, 0x0fab, 0x7f38, 0x0e1c, 0x7f62, 0x0c8c, 0x7f87, 0x0afb, 0x7fa7,
+    0x096b, 0x7fc2, 0x07d9, 0x7fd9, 0x0648, 0x7fea, 0x04b6, 0x7ff6, 0x0324,
+    0x7ffe, 0x0192, 0x7fff, 0x0000};
+
+struct RfftState {
+  int16_t* aligned_input;
+  int32_t fft_length;
+};
+
+size_t RfftInt16GetNeededMemory(int32_t fft_length) {
+  return sizeof(RfftState) + 2 * sizeof(int16_t) * fft_length;
+}
+
+void* RfftInt16Init(int32_t fft_length, void* state, size_t state_size) {
+  RfftState* rfft_state = (RfftState*)state;
+  int16_t* unaligned_buffer = (int16_t*)(rfft_state + 1);
+  rfft_state->aligned_input =
+      (int16_t*)((uint32_t)(unaligned_buffer + fft_length) &
+                 ~((1 << tflite::tflm_signal::MostSignificantBit32(
+                        fft_length)) -
+                   1));
+  rfft_state->fft_length = fft_length;
+  return state;
+}
+
+void RfftInt16Apply(void* state, const int16_t* input,
+                    Complex<int16_t>* output) {
+  RfftState* rfft_state = (RfftState*)state;
+  memcpy(rfft_state->aligned_input, input,
+         rfft_state->fft_length * sizeof(int16_t));
+  rfft(rfft_state->aligned_input, rfft_state->fft_length, (CWord2x16*)twiddles,
+       (CWord2x16*)rtwiddles, (CWord2x16*)output);
+  return;
+}
+
+}  // namespace tflm_signal

signal/micro/kernels/hexagon/square_root_32.cc

@@ -0,0 +1,28 @@
+/* Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+#include "signal/src/square_root.h"
+
+extern "C" uint16_t SignalHexagonSqrt32(uint32_t num);
+
+namespace tflite {
+namespace tflm_signal {
+
+// SignalHexagonSqrt32() is defined in assembly. This C wrapper is only
+// necessary to force TFLM's source specialization to pick up the optimized
+// Hexagon implementation instead of the portable one.
+uint16_t Sqrt32(uint32_t num) { return SignalHexagonSqrt32(num); }
+
+}  // namespace tflm_signal
+}  // namespace tflite