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@ -228,6 +228,113 @@ fdct_ifast (DCTELEM * data) |
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} |
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} |
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/*
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* Perform the forward 2-4-8 DCT on one block of samples. |
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*/ |
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GLOBAL(void) |
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fdct_ifast248 (DCTELEM * data) |
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{ |
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DCTELEM tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; |
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DCTELEM tmp10, tmp11, tmp12, tmp13; |
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DCTELEM z1, z2, z3, z4, z5, z11, z13; |
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DCTELEM *dataptr; |
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int ctr; |
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SHIFT_TEMPS |
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/* Pass 1: process rows. */ |
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dataptr = data; |
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for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { |
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tmp0 = dataptr[0] + dataptr[7]; |
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tmp7 = dataptr[0] - dataptr[7]; |
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tmp1 = dataptr[1] + dataptr[6]; |
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tmp6 = dataptr[1] - dataptr[6]; |
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tmp2 = dataptr[2] + dataptr[5]; |
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tmp5 = dataptr[2] - dataptr[5]; |
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tmp3 = dataptr[3] + dataptr[4]; |
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tmp4 = dataptr[3] - dataptr[4]; |
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/* Even part */ |
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tmp10 = tmp0 + tmp3; /* phase 2 */ |
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tmp13 = tmp0 - tmp3; |
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tmp11 = tmp1 + tmp2; |
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tmp12 = tmp1 - tmp2; |
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dataptr[0] = tmp10 + tmp11; /* phase 3 */ |
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dataptr[4] = tmp10 - tmp11; |
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z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); /* c4 */ |
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dataptr[2] = tmp13 + z1; /* phase 5 */ |
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dataptr[6] = tmp13 - z1; |
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/* Odd part */ |
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tmp10 = tmp4 + tmp5; /* phase 2 */ |
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tmp11 = tmp5 + tmp6; |
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tmp12 = tmp6 + tmp7; |
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/* The rotator is modified from fig 4-8 to avoid extra negations. */ |
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z5 = MULTIPLY(tmp10 - tmp12, FIX_0_382683433); /* c6 */ |
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z2 = MULTIPLY(tmp10, FIX_0_541196100) + z5; /* c2-c6 */ |
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z4 = MULTIPLY(tmp12, FIX_1_306562965) + z5; /* c2+c6 */ |
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z3 = MULTIPLY(tmp11, FIX_0_707106781); /* c4 */ |
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z11 = tmp7 + z3; /* phase 5 */ |
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z13 = tmp7 - z3; |
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dataptr[5] = z13 + z2; /* phase 6 */ |
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dataptr[3] = z13 - z2; |
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dataptr[1] = z11 + z4; |
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dataptr[7] = z11 - z4; |
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dataptr += DCTSIZE; /* advance pointer to next row */ |
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} |
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/* Pass 2: process columns. */ |
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dataptr = data; |
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for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { |
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tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1]; |
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tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3]; |
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tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5]; |
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tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7]; |
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tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1]; |
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tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3]; |
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tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5]; |
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tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7]; |
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/* Even part */ |
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tmp10 = tmp0 + tmp3; |
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tmp11 = tmp1 + tmp2; |
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tmp12 = tmp1 - tmp2; |
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tmp13 = tmp0 - tmp3; |
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dataptr[DCTSIZE*0] = tmp10 + tmp11; |
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dataptr[DCTSIZE*4] = tmp10 - tmp11; |
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z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); |
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dataptr[DCTSIZE*2] = tmp13 + z1; |
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dataptr[DCTSIZE*6] = tmp13 - z1; |
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tmp10 = tmp4 + tmp7; |
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tmp11 = tmp5 + tmp6; |
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tmp12 = tmp5 - tmp6; |
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tmp13 = tmp4 - tmp7; |
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dataptr[DCTSIZE*1] = tmp10 + tmp11; |
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dataptr[DCTSIZE*5] = tmp10 - tmp11; |
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z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); |
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dataptr[DCTSIZE*3] = tmp13 + z1; |
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dataptr[DCTSIZE*7] = tmp13 - z1; |
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dataptr++; /* advance pointer to next column */ |
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} |
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} |
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#undef GLOBAL |
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#undef CONST_BITS |
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