From 8736f6160aeafe7a177cb6143fea80157e174e52 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sun, 6 Oct 2024 19:47:19 +0200
Subject: Implement fixed-point symbols, FFT and file output

---
 kiss/kiss_fftndr.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 kiss/kiss_fftndr.c

(limited to 'kiss/kiss_fftndr.c')

diff --git a/kiss/kiss_fftndr.c b/kiss/kiss_fftndr.c
new file mode 100644
index 0000000..e979d03
--- /dev/null
+++ b/kiss/kiss_fftndr.c
@@ -0,0 +1,120 @@
+/*
+ *  Copyright (c) 2003-2004, Mark Borgerding. All rights reserved.
+ *  This file is part of KISS FFT - https://github.com/mborgerding/kissfft
+ *
+ *  SPDX-License-Identifier: BSD-3-Clause
+ *  See COPYING file for more information.
+ */
+
+#include "kiss_fftndr.h"
+#include "_kiss_fft_guts.h"
+#define MAX(x,y) ( ( (x)<(y) )?(y):(x) )
+
+struct kiss_fftndr_state
+{
+    int dimReal;
+    int dimOther;
+    kiss_fftr_cfg cfg_r;
+    kiss_fftnd_cfg cfg_nd;
+    void * tmpbuf;
+};
+
+static int prod(const int *dims, int ndims)
+{
+    int x=1;
+    while (ndims--) 
+        x *= *dims++;
+    return x;
+}
+
+kiss_fftndr_cfg kiss_fftndr_alloc(const int *dims,int ndims,int inverse_fft,void*mem,size_t*lenmem)
+{
+    KISS_FFT_ALIGN_CHECK(mem)
+
+    kiss_fftndr_cfg st = NULL;
+    size_t nr=0 , nd=0,ntmp=0;
+    int dimReal = dims[ndims-1];
+    int dimOther = prod(dims,ndims-1);
+    size_t memneeded;
+    char * ptr = NULL;
+
+    (void)kiss_fftr_alloc(dimReal,inverse_fft,NULL,&nr);
+    (void)kiss_fftnd_alloc(dims,ndims-1,inverse_fft,NULL,&nd);
+    ntmp =
+        MAX( 2*dimOther , dimReal+2) * sizeof(kiss_fft_scalar)  // freq buffer for one pass
+        + dimOther*(dimReal+2) * sizeof(kiss_fft_scalar);  // large enough to hold entire input in case of in-place
+
+    memneeded = KISS_FFT_ALIGN_SIZE_UP(sizeof( struct kiss_fftndr_state )) + KISS_FFT_ALIGN_SIZE_UP(nr) + KISS_FFT_ALIGN_SIZE_UP(nd) + KISS_FFT_ALIGN_SIZE_UP(ntmp);
+
+    if (lenmem==NULL) {
+        ptr = (char*) malloc(memneeded);
+    }else{
+        if (*lenmem >= memneeded)
+            ptr = (char *)mem;
+        *lenmem = memneeded; 
+    }
+    if (ptr==NULL)
+        return NULL;
+    
+    st = (kiss_fftndr_cfg) ptr;
+    memset( st , 0 , memneeded);
+    ptr += KISS_FFT_ALIGN_SIZE_UP(sizeof(struct kiss_fftndr_state));
+    
+    st->dimReal = dimReal;
+    st->dimOther = dimOther;
+    st->cfg_r = kiss_fftr_alloc( dimReal,inverse_fft,ptr,&nr);
+    ptr += KISS_FFT_ALIGN_SIZE_UP(nr);
+    st->cfg_nd = kiss_fftnd_alloc(dims,ndims-1,inverse_fft, ptr,&nd);
+    ptr += KISS_FFT_ALIGN_SIZE_UP(nd);
+    st->tmpbuf = ptr;
+
+    return st;
+}
+
+void kiss_fftndr(kiss_fftndr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_cpx *freqdata)
+{
+    int k1,k2;
+    int dimReal = st->dimReal;
+    int dimOther = st->dimOther;
+    int nrbins = dimReal/2+1;
+
+    kiss_fft_cpx * tmp1 = (kiss_fft_cpx*)st->tmpbuf; 
+    kiss_fft_cpx * tmp2 = tmp1 + MAX(nrbins,dimOther);
+
+    // timedata is N0 x N1 x ... x Nk real
+
+    // take a real chunk of data, fft it and place the output at correct intervals
+    for (k1=0;k1<dimOther;++k1) {
+        kiss_fftr( st->cfg_r, timedata + k1*dimReal , tmp1 ); // tmp1 now holds nrbins complex points
+        for (k2=0;k2<nrbins;++k2)
+           tmp2[ k2*dimOther+k1 ] = tmp1[k2];
+    }
+
+    for (k2=0;k2<nrbins;++k2) {
+        kiss_fftnd(st->cfg_nd, tmp2+k2*dimOther, tmp1);  // tmp1 now holds dimOther complex points
+        for (k1=0;k1<dimOther;++k1) 
+            freqdata[ k1*(nrbins) + k2] = tmp1[k1];
+    }
+}
+
+void kiss_fftndri(kiss_fftndr_cfg st,const kiss_fft_cpx *freqdata,kiss_fft_scalar *timedata)
+{
+    int k1,k2;
+    int dimReal = st->dimReal;
+    int dimOther = st->dimOther;
+    int nrbins = dimReal/2+1;
+    kiss_fft_cpx * tmp1 = (kiss_fft_cpx*)st->tmpbuf; 
+    kiss_fft_cpx * tmp2 = tmp1 + MAX(nrbins,dimOther);
+
+    for (k2=0;k2<nrbins;++k2) {
+        for (k1=0;k1<dimOther;++k1) 
+            tmp1[k1] = freqdata[ k1*(nrbins) + k2 ];
+        kiss_fftnd(st->cfg_nd, tmp1, tmp2+k2*dimOther);
+    }
+
+    for (k1=0;k1<dimOther;++k1) {
+        for (k2=0;k2<nrbins;++k2)
+            tmp1[k2] = tmp2[ k2*dimOther+k1 ];
+        kiss_fftri( st->cfg_r,tmp1,timedata + k1*dimReal);
+    }
+}
-- 
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