37 #define SIN(s, n, x) (s->costab[(n) - (x)])
40 #define COS(s, n, x) (s->costab[x])
44 int n = 1 << ctx->
nbits;
48 for (i = 1; i < n / 2; i++) {
49 float tmp1 = data[i ];
50 float tmp2 = data[n - i];
51 float s =
SIN(ctx, n, 2 * i);
54 tmp1 = (tmp1 - tmp2) * 0.5
f;
56 data[n - i] = s - tmp1;
64 for (i = 1; i < n - 2; i += 2) {
65 data[i + 1] += data[i - 1];
66 data[i] = -data[i + 2];
74 int n = 1 << ctx->
nbits;
76 float next = -0.5f * (data[0] - data[n]);
78 for (i = 0; i < n / 2; i++) {
80 float tmp2 = data[n - i];
81 float s =
SIN(ctx, n, 2 * i);
82 float c =
COS(ctx, n, 2 * i);
89 tmp1 = (tmp1 + tmp2) * 0.5
f;
91 data[n - i] = tmp1 + s;
98 for (i = 3; i <= n; i += 2)
99 data[i] = data[i - 2] - data[i];
104 int n = 1 << ctx->
nbits;
107 float next = data[n - 1];
108 float inv_n = 1.0f / n;
110 for (i = n - 2; i >= 2; i -= 2) {
111 float val1 = data[i];
112 float val2 = data[i - 1] - data[i + 1];
113 float c =
COS(ctx, n, i);
114 float s =
SIN(ctx, n, i);
116 data[i] = c * val1 + s * val2;
117 data[i + 1] = s * val1 - c * val2;
124 for (i = 0; i < n / 2; i++) {
125 float tmp1 = data[i] * inv_n;
126 float tmp2 = data[n - i - 1] * inv_n;
127 float csc = ctx->
csc2[i] * (tmp1 - tmp2);
130 data[i] = tmp1 + csc;
131 data[n - i - 1] = tmp1 - csc;
137 int n = 1 << ctx->
nbits;
141 for (i = 0; i < n / 2; i++) {
142 float tmp1 = data[i];
143 float tmp2 = data[n - i - 1];
144 float s =
SIN(ctx, n, 2 * i + 1);
147 tmp1 = (tmp1 + tmp2) * 0.5
f;
150 data[n-i-1] = tmp1 - s;
155 next = data[1] * 0.5;
158 for (i = n - 2; i >= 0; i -= 2) {
159 float inr = data[i ];
160 float ini = data[i + 1];
161 float c =
COS(ctx, n, i);
162 float s =
SIN(ctx, n, i);
164 data[i] = c * inr + s * ini;
167 next += s * inr - c * ini;
173 ctx->
dct32(data, data);
181 memset(s, 0,
sizeof(*s));
186 if (inverse ==
DCT_II && nbits == 5) {
191 s->
costab = ff_cos_tabs[nbits + 2];
199 for (i = 0; i < n / 2; i++)
200 s->
csc2[i] = 0.5 / sin((
M_PI / (2 * n) * (2 * i + 1)));