X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=imdct.c;h=5f48ba44c11b1186f6ebea4d5cec33b34e622bcc;hp=db68bc834764b125f1929785069de49131acfc7b;hb=1e012cf40238883621692051a22fb9c7cad5e944;hpb=537de45f0091a6129bc26602496384b464117863

diff --git a/imdct.c b/imdct.c
index db68bc83..5f48ba44 100644
--- a/imdct.c
+++ b/imdct.c
@@ -29,45 +29,55 @@
 
 typedef float fftsample_t;
 
+/** Canonical representation of a complex number. */
 struct fft_complex {
-	fftsample_t re, im;
+	/** Real part. */
+	fftsample_t re;
+	/** Imaginary part. */
+	fftsample_t im;
 };
 
+/** FFT Lookup table. */
 struct fft_context {
+	/** Number of bits of this instance of the FFT. */
 	int nbits;
+	/** The lookup table for cosine values. */
 	uint16_t *revtab;
 };
 
 struct mdct_context {
-	/** Size of MDCT (i.e. number of input data * 2). */
+	/** Size of MDCT (number of input data * 2). */
 	int n;
 	/** n = 2^n bits. */
 	int nbits;
-	/** pre/post rotation tables */
+	/** Cosine table for pre/post rotation. */
 	fftsample_t *tcos;
+	/** Sine table for pre/post rotation. */
 	fftsample_t *tsin;
+	/** The context for the underlying fast Fourier transform. */
 	struct fft_context fft;
 };
 
-/* cos(2*pi*x/n) for 0<=x<=n/4, followed by its reverse */
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_16[8]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_32[16]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_64[32]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_128[64]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_256[128]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_512[256]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_1024[512]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_2048[1024]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_4096[2048]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_8192[4096]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_16384[8192]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_32768[16384]);
-DECLARE_ALIGNED_16(fftsample_t, ff_cos_65536[32768]);
-
-static fftsample_t *ff_cos_tabs[] = {
-	ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256,
-	ff_cos_512, ff_cos_1024, ff_cos_2048, ff_cos_4096, ff_cos_8192,
-	ff_cos_16384, ff_cos_32768, ff_cos_65536,
+/** cos(2 * pi * x / n) for 0 <= x <= n / 4, followed by its reverse */
+#define COSINE_TAB(n) fftsample_t cos_ ## n[n / 2] __a_aligned(16)
+
+COSINE_TAB(16);
+COSINE_TAB(32);
+COSINE_TAB(64);
+COSINE_TAB(128);
+COSINE_TAB(256);
+COSINE_TAB(512);
+COSINE_TAB(1024);
+COSINE_TAB(2048);
+COSINE_TAB(4096);
+COSINE_TAB(8192);
+COSINE_TAB(16384);
+COSINE_TAB(32768);
+COSINE_TAB(65536);
+
+static fftsample_t *cos_tabs[] = {
+	cos_16, cos_32, cos_64, cos_128, cos_256, cos_512, cos_1024, cos_2048,
+	cos_4096, cos_8192, cos_16384, cos_32768, cos_65536,
 };
 
 static int split_radix_permutation(int i, int n)
@@ -85,85 +95,86 @@ static int split_radix_permutation(int i, int n)
 		return split_radix_permutation(i, m) * 4 - 1;
 }
 
-#define SQRTHALF (float)0.70710678118654752440	/* 1/sqrt(2) */
-
-#define BF(x,y,a,b) {\
-    x = a - b;\
-    y = a + b;\
+#define BF(x, y, a, b) {\
+	x = a - b;\
+	y = a + b;\
 }
 
-#define BUTTERFLIES(a0,a1,a2,a3) {\
-    BF(t3, t5, t5, t1);\
-    BF(a2.re, a0.re, a0.re, t5);\
-    BF(a3.im, a1.im, a1.im, t3);\
-    BF(t4, t6, t2, t6);\
-    BF(a3.re, a1.re, a1.re, t4);\
-    BF(a2.im, a0.im, a0.im, t6);\
+#define BUTTERFLIES(a0, a1, a2, a3) {\
+	BF(t3, t5, t5, t1);\
+	BF(a2.re, a0.re, a0.re, t5);\
+	BF(a3.im, a1.im, a1.im, t3);\
+	BF(t4, t6, t2, t6);\
+	BF(a3.re, a1.re, a1.re, t4);\
+	BF(a2.im, a0.im, a0.im, t6);\
 }
 
-// force loading all the inputs before storing any.
-// this is slightly slower for small data, but avoids store->load aliasing
-// for addresses separated by large powers of 2.
-#define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
-    fftsample_t r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
-    BF(t3, t5, t5, t1);\
-    BF(a2.re, a0.re, r0, t5);\
-    BF(a3.im, a1.im, i1, t3);\
-    BF(t4, t6, t2, t6);\
-    BF(a3.re, a1.re, r1, t4);\
-    BF(a2.im, a0.im, i0, t6);\
+/*
+ * Force loading all the inputs before storing any. This is slightly slower for
+ * small data, but avoids store->load aliasing for addresses separated by large
+ * powers of 2.
+ */
+#define BUTTERFLIES_BIG(a0, a1, a2, a3) {\
+	fftsample_t r0 = a0.re, i0 = a0.im, r1 = a1.re, i1 = a1.im;\
+	BF(t3, t5, t5, t1);\
+	BF(a2.re, a0.re, r0, t5);\
+	BF(a3.im, a1.im, i1, t3);\
+	BF(t4, t6, t2, t6);\
+	BF(a3.re, a1.re, r1, t4);\
+	BF(a2.im, a0.im, i0, t6);\
 }
 
-#define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
-    t1 = a2.re * wre + a2.im * wim;\
-    t2 = a2.im * wre - a2.re * wim;\
-    t5 = a3.re * wre - a3.im * wim;\
-    t6 = a3.im * wre + a3.re * wim;\
-    BUTTERFLIES(a0,a1,a2,a3)\
+#define TRANSFORM(a0, a1, a2, a3, wre,wim) {\
+	t1 = a2.re * wre + a2.im * wim;\
+	t2 = a2.im * wre - a2.re * wim;\
+	t5 = a3.re * wre - a3.im * wim;\
+	t6 = a3.im * wre + a3.re * wim;\
+	BUTTERFLIES(a0, a1, a2, a3)\
 }
 
-#define TRANSFORM_ZERO(a0,a1,a2,a3) {\
-    t1 = a2.re;\
-    t2 = a2.im;\
-    t5 = a3.re;\
-    t6 = a3.im;\
-    BUTTERFLIES(a0,a1,a2,a3)\
+#define TRANSFORM_ZERO(a0, a1, a2, a3) {\
+	t1 = a2.re;\
+	t2 = a2.im;\
+	t5 = a3.re;\
+	t6 = a3.im;\
+	BUTTERFLIES(a0, a1, a2, a3)\
 }
 
-/* z[0...8n-1], w[1...2n-1] */
+/* z[0...8n - 1], w[1...2n - 1] */
 #define PASS(name)\
 static void name(struct fft_complex *z, const fftsample_t *wre, unsigned int n)\
 {\
-    fftsample_t t1, t2, t3, t4, t5, t6;\
-    int o1 = 2*n;\
-    int o2 = 4*n;\
-    int o3 = 6*n;\
-    const fftsample_t *wim = wre+o1;\
-    n--;\
+	fftsample_t t1, t2, t3, t4, t5, t6;\
+	int o1 = 2 * n;\
+	int o2 = 4 * n;\
+	int o3 = 6 * n;\
+	const fftsample_t *wim = wre + o1;\
+	n--;\
 \
-    TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
-    TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
-    do {\
-        z += 2;\
-        wre += 2;\
-        wim -= 2;\
-        TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
-        TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
-    } while(--n);\
+	TRANSFORM_ZERO(z[0], z[o1], z[o2], z[o3]);\
+	TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);\
+	do {\
+		z += 2;\
+		wre += 2;\
+		wim -= 2;\
+		TRANSFORM(z[0], z[o1], z[o2], z[o3], wre[0], wim[0]);\
+		TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);\
+	} while (--n);\
 }
 
 PASS(pass)
 #undef BUTTERFLIES
 #define BUTTERFLIES BUTTERFLIES_BIG
 
-#define DECL_FFT(n,n2,n4)\
+#define DECL_FFT(n, n2, n4)\
 static void fft##n(struct fft_complex *z)\
 {\
-    fft##n2(z);\
-    fft##n4(z+n4*2);\
-    fft##n4(z+n4*3);\
-    pass(z,ff_cos_##n,n4/2);\
+	fft ## n2(z);\
+	fft ## n4(z + n4 * 2);\
+	fft ## n4(z + n4 * 3);\
+	pass(z, cos_ ## n, n4 / 2);\
 }
+
 static void fft4(struct fft_complex *z)
 {
 	fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
@@ -195,7 +206,7 @@ static void fft8(struct fft_complex *z)
 	BF(z[6].re, z[2].re, z[2].re, t7);
 	BF(z[6].im, z[2].im, z[2].im, t8);
 
-	TRANSFORM(z[1], z[3], z[5], z[7], SQRTHALF, SQRTHALF);
+	TRANSFORM(z[1], z[3], z[5], z[7], M_SQRT1_2, M_SQRT1_2);
 }
 
 static void fft16(struct fft_complex *z)
@@ -207,9 +218,9 @@ static void fft16(struct fft_complex *z)
 	fft4(z + 12);
 
 	TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
-	TRANSFORM(z[2], z[6], z[10], z[14], SQRTHALF, SQRTHALF);
-	TRANSFORM(z[1], z[5], z[9], z[13], ff_cos_16[1], ff_cos_16[3]);
-	TRANSFORM(z[3], z[7], z[11], z[15], ff_cos_16[3], ff_cos_16[1]);
+	TRANSFORM(z[2], z[6], z[10], z[14], M_SQRT1_2, M_SQRT1_2);
+	TRANSFORM(z[1], z[5], z[9], z[13], cos_16[1], cos_16[3]);
+	TRANSFORM(z[3], z[7], z[11], z[15], cos_16[3], cos_16[1]);
 }
 
 DECL_FFT(32, 16, 8)
@@ -297,19 +308,22 @@ static void imdct_half(struct mdct_context *s, fftsample_t *output,
 }
 
 /**
- * Compute the inverse MDCT of size N = 2^nbits.
+ * Compute the inverse MDCT.
  *
+ * \param ctx The initialized context structure.
  * \param output N samples.
  * \param input N/2 samples.
+ *
+ * \sa \ref imdct_init().
  */
-void imdct(struct mdct_context *s, float *output, const float *input)
+void imdct(struct mdct_context *ctx, float *output, const float *input)
 {
 	int k;
-	int n = 1 << s->nbits;
+	int n = 1 << ctx->nbits;
 	int n2 = n >> 1;
 	int n4 = n >> 2;
 
-	imdct_half(s, output + n4, input);
+	imdct_half(ctx, output + n4, input);
 
 	for (k = 0; k < n4; k++) {
 		output[k] = -output[n2 - k - 1];
@@ -330,7 +344,7 @@ static int fft_init(struct fft_context *s, int nbits)
 	for (j = 4; j <= nbits; j++) {
 		int k = 1 << j;
 		double freq = 2 * M_PI / k;
-		fftsample_t *tab = ff_cos_tabs[j - 4];
+		fftsample_t *tab = cos_tabs[j - 4];
 		for (i = 0; i <= k / 4; i++)
 			tab[i] = cos(i * freq);
 		for (i = 1; i < k / 4; i++)
@@ -343,6 +357,12 @@ static int fft_init(struct fft_context *s, int nbits)
 
 /**
  * Initialize the inverse modified cosine transform.
+ *
+ * \param nbits The number of bits to use (4 <= \a nbits <= 18).
+ *
+ * \param result Opaque structure that must be passed to \ref imdct().
+ *
+ * \return Standard.
  */
 int imdct_init(int nbits, struct mdct_context **result)
 {
@@ -375,10 +395,15 @@ fail:
 	return ret;
 }
 
+/**
+ * Deallocate imdct resources.
+ *
+ * \param ctx The pointer obtained by imdct_init().
+ */
 void imdct_end(struct mdct_context *ctx)
 {
-	freep(&ctx->tcos);
-	freep(&ctx->tsin);
-	freep(&ctx->fft.revtab);
+	free(ctx->tcos);
+	free(ctx->tsin);
+	free(ctx->fft.revtab);
 	free(ctx);
 }