feat: add initial implementaion of fft/base/fftpack

lib/node_modules/@stdlib/fft/base/fftpack/lib/c1_ref.js

@@ -0,0 +1,81 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* 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.
+*
+*
+* ## Notice
+*
+* The original C code and copyright notice are from the [PFFFT library]{@link https://github.com/marton78/pffft/blob/master/fftpack.c}. The implementation follows the original, but has been modified for JavaScript.
+*
+* ```text
+* Copyright (c) 2004 the University Corporation for Atmospheric
+* Research ("UCAR"). All rights reserved. Developed by NCAR's
+* Computational and Information Systems Laboratory, UCAR,
+* www.cisl.ucar.edu.
+*
+* Redistribution and use of the Software in source and binary forms,
+* with or without modification, is permitted provided that the
+* following conditions are met:
+*
+*     - Neither the names of NCAR's Computational and Information Systems
+*       Laboratory, the University Corporation for Atmospheric Research,
+*       nor the names of its sponsors or contributors may be used to
+*       endorse or promote products derived from this Software without
+*       specific prior written permission.
+*
+*     - Redistributions of source code must retain the above copyright
+*       notices, this list of conditions, and the disclaimer below.
+*
+*     - Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions, and the disclaimer below in the
+*       documentation and/or other materials provided with the
+*       distribution.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
+* HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
+* EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+* SOFTWARE.
+* ```
+*/
+
+'use strict';
+
+// MAIN //
+
+/**
+* Performs a pass of the FFT algorithm.
+*
+* @private
+* @param {number} a1 - index of first dimension
+* @param {number} a2 - index of second dimension
+* @param {number} a3 - index of third dimension
+* @param {number} l1 - length parameter related to the FFT stage
+* @param {number} ido - dimension order
+* @returns {number} - calculated index
+*/
+function c1Ref( a1, a2, a3, l1, ido ) {
+	return ( ( ( a3 * l1 ) + a2 ) * ido ) + a1;
+}
+
+
+// EXPORTS //
+
+module.exports = c1Ref;

lib/node_modules/@stdlib/fft/base/fftpack/lib/c2_ref.js

@@ -0,0 +1,79 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* 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.
+*
+*
+* ## Notice
+*
+* The original C code and copyright notice are from the [PFFFT library]{@link https://github.com/marton78/pffft/blob/master/fftpack.c}. The implementation follows the original, but has been modified for JavaScript.
+*
+* ```text
+* Copyright (c) 2004 the University Corporation for Atmospheric
+* Research ("UCAR"). All rights reserved. Developed by NCAR's
+* Computational and Information Systems Laboratory, UCAR,
+* www.cisl.ucar.edu.
+*
+* Redistribution and use of the Software in source and binary forms,
+* with or without modification, is permitted provided that the
+* following conditions are met:
+*
+*     - Neither the names of NCAR's Computational and Information Systems
+*       Laboratory, the University Corporation for Atmospheric Research,
+*       nor the names of its sponsors or contributors may be used to
+*       endorse or promote products derived from this Software without
+*       specific prior written permission.
+*
+*     - Redistributions of source code must retain the above copyright
+*       notices, this list of conditions, and the disclaimer below.
+*
+*     - Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions, and the disclaimer below in the
+*       documentation and/or other materials provided with the
+*       distribution.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
+* HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
+* EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+* SOFTWARE.
+* ```
+*/
+
+'use strict';
+
+// MAIN //
+
+/**
+* Performs a pass of the FFT algorithm.
+*
+* @private
+* @param {number} a1 - index of first dimension
+* @param {number} a2 - index of second dimension
+* @param {number} idl1 - stride related to the `l1` parameter
+* @returns {number} - calculated index
+*/
+function c2Ref( a1, a2, idl1 ) {
+	return ( a2 * idl1 ) + a1;
+}
+
+
+// EXPORTS //
+
+module.exports = c2Ref;

lib/node_modules/@stdlib/fft/base/fftpack/lib/cc_ref.js

@@ -0,0 +1,81 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* 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.
+*
+*
+* ## Notice
+*
+* The original C code and copyright notice are from the [PFFFT library]{@link https://github.com/marton78/pffft/blob/master/fftpack.c}. The implementation follows the original, but has been modified for JavaScript.
+*
+* ```text
+* Copyright (c) 2004 the University Corporation for Atmospheric
+* Research ("UCAR"). All rights reserved. Developed by NCAR's
+* Computational and Information Systems Laboratory, UCAR,
+* www.cisl.ucar.edu.
+*
+* Redistribution and use of the Software in source and binary forms,
+* with or without modification, is permitted provided that the
+* following conditions are met:
+*
+*     - Neither the names of NCAR's Computational and Information Systems
+*       Laboratory, the University Corporation for Atmospheric Research,
+*       nor the names of its sponsors or contributors may be used to
+*       endorse or promote products derived from this Software without
+*       specific prior written permission.
+*
+*     - Redistributions of source code must retain the above copyright
+*       notices, this list of conditions, and the disclaimer below.
+*
+*     - Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions, and the disclaimer below in the
+*       documentation and/or other materials provided with the
+*       distribution.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
+* HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
+* EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+* SOFTWARE.
+* ```
+*/
+
+'use strict';
+
+// MAIN //
+
+/**
+* Performs a pass of the FFT algorithm.
+*
+* @private
+* @param {number} a1 - index of first dimension
+* @param {number} a2 - index of second dimension
+* @param {number} a3 - index of third dimension
+* @param {number} ip - number of sub-steps or prime factors in the FFT
+* @param {number} ido - dimension order
+* @returns {number} - calculated index
+*/
+function ccRef( a1, a2, a3, ip, ido ) {
+	return ( ( ( a3 * ip ) + a2 ) * ido ) + a1;
+}
+
+
+// EXPORTS //
+
+module.exports = ccRef;

lib/node_modules/@stdlib/fft/base/fftpack/lib/cfftb.js

@@ -0,0 +1,96 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* 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.
+*
+*
+* ## Notice
+*
+* The original C code and copyright notice are from the [PFFFT library]{@link https://github.com/marton78/pffft/blob/master/fftpack.c}. The implementation follows the original, but has been modified for JavaScript.
+*
+* ```text
+* Copyright (c) 2004 the University Corporation for Atmospheric
+* Research ("UCAR"). All rights reserved. Developed by NCAR's
+* Computational and Information Systems Laboratory, UCAR,
+* www.cisl.ucar.edu.
+*
+* Redistribution and use of the Software in source and binary forms,
+* with or without modification, is permitted provided that the
+* following conditions are met:
+*
+*     - Neither the names of NCAR's Computational and Information Systems
+*       Laboratory, the University Corporation for Atmospheric Research,
+*       nor the names of its sponsors or contributors may be used to
+*       endorse or promote products derived from this Software without
+*       specific prior written permission.
+*
+*     - Redistributions of source code must retain the above copyright
+*       notices, this list of conditions, and the disclaimer below.
+*
+*     - Redistributions in binary form must reproduce the above copyright
+*       notice, this list of conditions, and the disclaimer below in the
+*       documentation and/or other materials provided with the
+*       distribution.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+* NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
+* HOLDERS BE LIABLE FOR ANY CLAIM, INDIRECT, INCIDENTAL, SPECIAL,
+* EXEMPLARY, OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+* SOFTWARE.
+* ```
+*/
+
+'use strict';
+
+// MODULES //
+
+var cfftb1 = require( './cfftb1.js' );
+
+
+// MAIN //
+
+/**
+* Performs the complex backward Fast Fourier Transform.
+*
+* @param {number} n - length of the sequence to transform
+* @param {Float64Array} c - input array containing sequence to be transformed
+* @param {number} cptr - starting index for c
+* @param {Float64Array} wsave - working array containing precomputed values
+* @param {number} wptr - starting index for wsave
+* @returns {void}
+*/
+function cfftb( n, c, cptr, wsave, wptr ) {
+	var iw1;
+	var iw2;
+
+	wptr -= 1;
+	cptr -= 1;
+
+	if ( n === 1 ) {
+		return;
+	}
+	iw1 = ( 2 * n ) + 1;
+	iw2 = iw1 + ( 2 * n );
+	cfftb1( n, c, cptr, wsave, wptr, wsave, wptr + iw1, wsave, wptr + iw2 );
+}
+
+
+// EXPORTS //
+
+module.exports = cfftb;