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29 * Author: Nedeljko Babic (nbabic@mips.com)
31 * This file is part of FFmpeg.
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45 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
48 #ifndef AVUTIL_FIXED_DSP_H
49 #define AVUTIL_FIXED_DSP_H
52 #include "attributes.h"
54 #include "libavcodec/mathops.h"
56 typedef struct AVFixedDSPContext {
58 * Overlap/add with window function.
59 * Used primarily by MDCT-based audio codecs.
60 * Source and destination vectors must overlap exactly or not at all.
62 * @param dst result vector
63 * constraints: 16-byte aligned
64 * @param src0 first source vector
65 * constraints: 16-byte aligned
66 * @param src1 second source vector
67 * constraints: 16-byte aligned
68 * @param win half-window vector
69 * constraints: 16-byte aligned
70 * @param len length of vector
71 * constraints: multiple of 4
72 * @param bits scaling parameter
75 void (*vector_fmul_window_scaled)(int16_t *dst, const int32_t *src0, const int32_t *src1, const int32_t *win, int len, uint8_t bits);
78 * Overlap/add with window function.
79 * Used primarily by MDCT-based audio codecs.
80 * Source and destination vectors must overlap exactly or not at all.
82 * @param dst result vector
83 * constraints: 32-byte aligned
84 * @param src0 first source vector
85 * constraints: 16-byte aligned
86 * @param src1 second source vector
87 * constraints: 16-byte aligned
88 * @param win half-window vector
89 * constraints: 16-byte aligned
90 * @param len length of vector
91 * constraints: multiple of 4
93 void (*vector_fmul_window)(int32_t *dst, const int32_t *src0, const int32_t *src1, const int32_t *win, int len);
98 * Allocate and initialize a fixed DSP context.
99 * note: should be freed with a av_free call when no longer needed.
101 * @param strict setting to non-zero avoids using functions which may not be IEEE-754 compliant
103 AVFixedDSPContext * avpriv_alloc_fixed_dsp(int strict);
106 * Calculate the square root
108 * @param x input fixed point number
110 * @param bits format of fixed point number (32 - bits).bits
112 * note: input is normalized to (0, 1) fixed point value
115 static av_always_inline int fixed_sqrt(int x, int bits)
117 int retval, bit_mask, guess, square, i;
119 int shift1 = 30 - bits;
120 int shift2 = bits - 15;
122 if (shift1 > 0) retval = ff_sqrt(x << shift1);
123 else retval = ff_sqrt(x >> -shift1);
126 retval = retval << shift2;
127 bit_mask = (1 << (shift2 - 1));
129 for (i=0; i<shift2; i++){
130 guess = retval + bit_mask;
131 accu = (int64_t)guess * guess;
132 square = (int)((accu + bit_mask) >> bits);
139 else retval >>= (-shift2);
144 #endif /* AVUTIL_FIXED_DSP_H */