Audio: STFT Process: Remove unused fill_start_idx

This patch removes fill_start_idx member from struct stft_process_fft.
It would have required another check for data align and samples amount
for Xtensa HIFI SIMD code version. There is no need for different FFT
padding types (left, center, right as in MFCC) in this component, so
it's safe to remove.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/audio/stft_process/stft_process-generic.c

@@ -18,7 +18,7 @@ void stft_process_overlap_add_ifft_buffer(struct stft_process_state *state, int
 	int i;
 	int n;
 	int samples_remain = fft->fft_size;
-	int idx = fft->fft_fill_start_idx;
+	int idx = 0;
 
 	while (samples_remain) {
 		n = stft_process_buffer_samples_without_wrap(obuf, w);
@@ -49,12 +49,11 @@ void stft_process_apply_window(struct stft_process_state *state)
 {
 	struct stft_process_fft *fft = &state->fft;
 	int j;
-	int i = fft->fft_fill_start_idx;
 
 	/* Multiply Q1.31 by Q1.15 gives Q2.46, shift right by 15 to get Q2.31, no saturate need */
 	for (j = 0; j < fft->fft_size; j++)
-		fft->fft_buf[i + j].real =
-			sat_int32(Q_MULTSR_32X32((int64_t)fft->fft_buf[i + j].real,
+		fft->fft_buf[j].real =
+			sat_int32(Q_MULTSR_32X32((int64_t)fft->fft_buf[j].real,
 						 state->window[j], 31, 31, 31));
 }
 #endif /* SOF_USE_HIFI(NONE, COMP_STFT_PROCESS) */

src/audio/stft_process/stft_process-hifi3.c

@@ -37,7 +37,6 @@ void stft_process_apply_window(struct stft_process_state *state)
 	ae_f32x2 win01, win23;
 	ae_int32x2 d0, d1;
 	int fft_size = fft->fft_size;
-	int i = fft->fft_fill_start_idx;
 	int j;
 	int n4;
 
@@ -52,7 +51,7 @@ void stft_process_apply_window(struct stft_process_state *state)
 	 * Stride for buf  is sizeof(ae_int32x2) = 8 bytes per complex sample.
 	 * Stride for win  is sizeof(ae_int32)   = 4 bytes per scalar window value.
 	 */
-	buf = (ae_int32 *)&fft->fft_buf[i];
+	buf = (ae_int32 *)fft->fft_buf;
 	win = (const ae_int32x2 *)state->window;
 
 	assert(!(fft_size & 3));
@@ -109,7 +108,7 @@ void stft_process_overlap_add_ifft_buffer(struct stft_process_state *state, int
 	ae_f32x2 fft_data;
 	ae_f32x2 d0, d1;
 	ae_f32x2 *w = (ae_f32x2 *)obuf->w_ptr;
-	ae_f32 *fft_p = (ae_f32 *)&fft->fft_buf[fft->fft_fill_start_idx];
+	ae_f32 *fft_p = (ae_f32 *)fft->fft_buf;
 	int samples_remain = fft->fft_size;
 	int i, n;
 

src/audio/stft_process/stft_process.h

@@ -66,7 +66,6 @@ struct stft_process_fft {
 	struct ipolar32 *fft_polar;
 	struct fft_multi_plan *fft_plan;
 	struct fft_multi_plan *ifft_plan;
-	int fft_fill_start_idx; /**< Set to 0 for pad left, etc. */
 	int fft_size;
 	int fft_padded_size;
 	int fft_hop_size;

src/audio/stft_process/stft_process_setup.c

@@ -180,8 +180,6 @@ int stft_process_setup(struct processing_module *mod, int max_frames,
 	/* Share the fft_out buffer for polar format */
 	fft->fft_polar = (struct ipolar32 *)fft->fft_out;
 
-	fft->fft_fill_start_idx = 0; /* From config pad_type */
-
 	/* Setup FFT */
 	fft->fft_plan = mod_fft_multi_plan_new(mod, fft->fft_buf, fft->fft_out,
 					       fft->fft_padded_size, 32);