Initial dct modules with dummy main.

forward dct compiles cleanly. Needs to be verified if working.
inverse dct needs some type fixing (from original libjpeg).

5 files changed, 346 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..e7eff81
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -o test src/main.c src/fdct.c -I include/
diff --git a/include/dct.h b/include/dct.h
new file mode 100644
index 0000000..d202de5
--- /dev/null
+++ b/include/dct.h
@@ -0,0 +1,11 @@
+#define CONST_BITS  8
+#define DCTSIZE 8
+#define DCTSIZE_BLOCK (DCTSIZE * DCTSIZE)
+
+#define RIGHT_SHIFT(x,shft)	((x) >> (shft))
+
+#define DESCALE(x,n)	RIGHT_SHIFT((x) + (1 << ((n)-1)), n)
+
+#define MULTIPLY(var,constant)	(DESCALE((var) * (constant), CONST_BITS))
+
+void fdct(int *data);
diff --git a/src/fdct.c b/src/fdct.c
new file mode 100644
index 0000000..3631de6
--- /dev/null
+++ b/src/fdct.c
@@ -0,0 +1,118 @@
+#include "dct.h"
+
+#define FIX_0_382683433  (98)		/* FIX(0.382683433) */
+#define FIX_0_541196100  (139)		/* FIX(0.541196100) */
+#define FIX_0_707106781  (181)		/* FIX(0.707106781) */
+#define FIX_1_306562965  (334)		/* FIX(1.306562965) */
+
+/*
+ * Perform the forward DCT on one block of samples.
+ */
+void fdct(int *data) {
+	int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
+	int tmp10, tmp11, tmp12, tmp13;
+	int z1, z2, z3, z4, z5, z11, z13;
+	int *dataptr;
+	int ctr;
+//	SHIFT_TEMPS
+
+	/* Pass 1: process rows. */
+
+	dataptr = data;
+	for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
+		tmp0 = dataptr[0] + dataptr[7];
+		tmp7 = dataptr[0] - dataptr[7];
+		tmp1 = dataptr[1] + dataptr[6];
+		tmp6 = dataptr[1] - dataptr[6];
+		tmp2 = dataptr[2] + dataptr[5];
+		tmp5 = dataptr[2] - dataptr[5];
+		tmp3 = dataptr[3] + dataptr[4];
+		tmp4 = dataptr[3] - dataptr[4];
+    
+		/* Even part */
+    
+		tmp10 = tmp0 + tmp3;	/* phase 2 */
+		tmp13 = tmp0 - tmp3;
+		tmp11 = tmp1 + tmp2;
+		tmp12 = tmp1 - tmp2;
+    
+		dataptr[0] = tmp10 + tmp11; /* phase 3 */
+		dataptr[4] = tmp10 - tmp11;
+
+		z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); /* c4 */
+		dataptr[2] = tmp13 + z1;	/* phase 5 */
+		dataptr[6] = tmp13 - z1;
+   
+		/* Odd part */
+
+		tmp10 = tmp4 + tmp5;	/* phase 2 */
+		tmp11 = tmp5 + tmp6;
+		tmp12 = tmp6 + tmp7;
+		
+		/* The rotator is modified from fig 4-8 to avoid extra negations. */
+		z5 = MULTIPLY(tmp10 - tmp12, FIX_0_382683433); /* c6 */
+		z2 = MULTIPLY(tmp10, FIX_0_541196100) + z5; /* c2-c6 */
+		z4 = MULTIPLY(tmp12, FIX_1_306562965) + z5; /* c2+c6 */
+		z3 = MULTIPLY(tmp11, FIX_0_707106781); /* c4 */
+
+		z11 = tmp7 + z3;		/* phase 5 */
+		z13 = tmp7 - z3;
+
+		dataptr[5] = z13 + z2;	/* phase 6 */
+		dataptr[3] = z13 - z2;
+		dataptr[1] = z11 + z4;
+		dataptr[7] = z11 - z4;
+		
+		dataptr += DCTSIZE;		/* advance pointer to next row */
+	}
+
+	/* Pass 2: process columns. */
+
+	dataptr = data;
+	for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
+		tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7];
+		tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7];
+		tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6];
+		tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6];
+		tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5];
+		tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5];
+		tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4];
+		tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4];
+    
+		/* Even part */
+
+		tmp10 = tmp0 + tmp3;	/* phase 2 */
+		tmp13 = tmp0 - tmp3;
+		tmp11 = tmp1 + tmp2;
+		tmp12 = tmp1 - tmp2;
+    
+		dataptr[DCTSIZE*0] = tmp10 + tmp11; /* phase 3 */
+		dataptr[DCTSIZE*4] = tmp10 - tmp11;
+    
+		z1 = MULTIPLY(tmp12 + tmp13, FIX_0_707106781); /* c4 */
+		dataptr[DCTSIZE*2] = tmp13 + z1; /* phase 5 */
+		dataptr[DCTSIZE*6] = tmp13 - z1;
+
+		/* Odd part */
+
+		tmp10 = tmp4 + tmp5;	/* phase 2 */
+		tmp11 = tmp5 + tmp6;
+		tmp12 = tmp6 + tmp7;
+		
+		/* The rotator is modified from fig 4-8 to avoid extra negations. */
+		z5 = MULTIPLY(tmp10 - tmp12, FIX_0_382683433); /* c6 */
+		z2 = MULTIPLY(tmp10, FIX_0_541196100) + z5; /* c2-c6 */
+		z4 = MULTIPLY(tmp12, FIX_1_306562965) + z5; /* c2+c6 */
+		z3 = MULTIPLY(tmp11, FIX_0_707106781); /* c4 */
+
+		z11 = tmp7 + z3;		/* phase 5 */
+		z13 = tmp7 - z3;
+
+		dataptr[DCTSIZE*5] = z13 + z2; /* phase 6 */
+		dataptr[DCTSIZE*3] = z13 - z2;
+		dataptr[DCTSIZE*1] = z11 + z4;
+		dataptr[DCTSIZE*7] = z11 - z4;
+
+		dataptr++;			/* advance pointer to next column */
+	}
+}
diff --git a/src/idct.c b/src/idct.c
new file mode 100644
index 0000000..082a41a
--- /dev/null
+++ b/src/idct.c
@@ -0,0 +1,201 @@
+#define CONST_BITS  8
+#define PASS1_BITS  2
+
+#define FIX_1_082392200  ((INT32)  277)		/* FIX(1.082392200) */
+#define FIX_1_414213562  ((INT32)  362)		/* FIX(1.414213562) */
+#define FIX_1_847759065  ((INT32)  473)		/* FIX(1.847759065) */
+#define FIX_2_613125930  ((INT32)  669)		/* FIX(2.613125930) */
+
+#define DEQUANTIZE(coef,quantval)  (((coef)) * (quantval))
+
+/*
+ * Perform dequantization and inverse DCT on one block of coefficients.
+ */
+
+void idct (j_decompress_ptr cinfo, jpeg_component_info * compptr,
+		 int FAR *coef_block,
+		 JSAMPARRAY output_buf, JDIMENSION output_col) {
+	int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
+	int tmp10, tmp11, tmp12, tmp13;
+	int z5, z10, z11, z12, z13;
+	int inptr;
+	int * quantptr;
+	int * wsptr;
+	JSAMPROW outptr;
+	JSAMPLE *range_limit = IDCT_range_limit(cinfo);
+	int ctr;
+	int workspace[DCTSIZE2];	/* buffers data between passes */
+	SHIFT_TEMPS			/* for DESCALE */
+	ISHIFT_TEMPS			/* for IDESCALE */
+
+	/* Pass 1: process columns from input, store into work array. */
+
+	inptr = coef_block;
+	quantptr = (IFAST_MULT_TYPE *) compptr->dct_table;
+	wsptr = workspace;
+	for (ctr = DCTSIZE; ctr > 0; ctr--) {
+	/* Due to quantization, we will usually find that many of the input
+	 * coefficients are zero, especially the AC terms.  We can exploit this
+	 * by short-circuiting the IDCT calculation for any column in which all
+	 * the AC terms are zero.  In that case each output is equal to the
+	 * DC coefficient (with scale factor as needed).
+	 */
+		
+		if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 &&
+			inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 &&
+			inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 &&
+			inptr[DCTSIZE*7] == 0) {
+			/* AC terms all zero */
+			int dcval = (int) DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
+
+			wsptr[DCTSIZE*0] = dcval;
+			wsptr[DCTSIZE*1] = dcval;
+			wsptr[DCTSIZE*2] = dcval;
+			wsptr[DCTSIZE*3] = dcval;
+			wsptr[DCTSIZE*4] = dcval;
+			wsptr[DCTSIZE*5] = dcval;
+			wsptr[DCTSIZE*6] = dcval;
+			wsptr[DCTSIZE*7] = dcval;
+
+			inptr++;			/* advance pointers to next column */
+			quantptr++;
+			wsptr++;
+			continue;
+		}
+    
+		/* Even part */
+
+		tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
+		tmp1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
+		tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
+		tmp3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
+
+		tmp10 = tmp0 + tmp2;	/* phase 3 */
+		tmp11 = tmp0 - tmp2;
+
+		tmp13 = tmp1 + tmp3;	/* phases 5-3 */
+		tmp12 = MULTIPLY(tmp1 - tmp3, FIX_1_414213562) - tmp13; /* 2*c4 */
+
+		tmp0 = tmp10 + tmp13;	/* phase 2 */
+		tmp3 = tmp10 - tmp13;
+		tmp1 = tmp11 + tmp12;
+		tmp2 = tmp11 - tmp12;
+    
+		/* Odd part */
+
+		tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);
+		tmp5 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
+		tmp6 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
+		tmp7 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);
+
+		z13 = tmp6 + tmp5;		/* phase 6 */
+		z10 = tmp6 - tmp5;
+		z11 = tmp4 + tmp7;
+		z12 = tmp4 - tmp7;
+
+		tmp7 = z11 + z13;		/* phase 5 */
+		tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); /* 2*c4 */
+
+		z5 = MULTIPLY(z10 + z12, FIX_1_847759065); /* 2*c2 */
+		tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; /* 2*(c2-c6) */
+		tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; /* -2*(c2+c6) */
+
+		tmp6 = tmp12 - tmp7;	/* phase 2 */
+		tmp5 = tmp11 - tmp6;
+		tmp4 = tmp10 + tmp5;
+
+		wsptr[DCTSIZE*0] = (int) (tmp0 + tmp7);
+		wsptr[DCTSIZE*7] = (int) (tmp0 - tmp7);
+		wsptr[DCTSIZE*1] = (int) (tmp1 + tmp6);
+		wsptr[DCTSIZE*6] = (int) (tmp1 - tmp6);
+		wsptr[DCTSIZE*2] = (int) (tmp2 + tmp5);
+		wsptr[DCTSIZE*5] = (int) (tmp2 - tmp5);
+		wsptr[DCTSIZE*4] = (int) (tmp3 + tmp4);
+		wsptr[DCTSIZE*3] = (int) (tmp3 - tmp4);
+
+		inptr++;			/* advance pointers to next column */
+		quantptr++;
+		wsptr++;
+	}
+  
+	/* Pass 2: process rows from work array, store into output array.
+	 * Note that we must descale the results by a factor of 8 == 2**3,
+	 * and also undo the PASS1_BITS scaling.
+	 */
+
+	wsptr = workspace;
+	for (ctr = 0; ctr < DCTSIZE; ctr++) {
+		outptr = output_buf[ctr] + output_col;
+		/* Rows of zeroes can be exploited in the same way as we did with columns.
+		 * However, the column calculation has created many nonzero AC terms, so
+		 * the simplification applies less often (typically 5% to 10% of the time).
+		 * on machines with very fast multiplication, it's possible that the
+		 * test takes more time than it's worth.  In that case this section
+		 * may be commented out.
+		 */
+    
+#ifndef NO_ZERO_ROW_TEST
+		if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && wsptr[4] == 0 &&
+			wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) {
+			/* AC terms all zero */
+			JSAMPLE dcval = range_limit[IDESCALE(wsptr[0], PASS1_BITS+3) & RANGE_MASK];
+
+			outptr[0] = dcval;
+			outptr[1] = dcval;
+			outptr[2] = dcval;
+			outptr[3] = dcval;
+			outptr[4] = dcval;
+			outptr[5] = dcval;
+			outptr[6] = dcval;
+			outptr[7] = dcval;
+
+			wsptr += DCTSIZE;		/* advance pointer to next row */
+			continue;
+		}
+#endif
+    
+		/* Even part */
+
+		tmp10 = ((DCTELEM) wsptr[0] + (DCTELEM) wsptr[4]);
+		tmp11 = ((DCTELEM) wsptr[0] - (DCTELEM) wsptr[4]);
+
+		tmp13 = ((DCTELEM) wsptr[2] + (DCTELEM) wsptr[6]);
+		tmp12 = MULTIPLY((DCTELEM) wsptr[2] - (DCTELEM) wsptr[6], FIX_1_414213562) - tmp13;
+
+		tmp0 = tmp10 + tmp13;
+		tmp3 = tmp10 - tmp13;
+		tmp1 = tmp11 + tmp12;
+		tmp2 = tmp11 - tmp12;
+
+		/* Odd part */
+
+		z13 = (DCTELEM) wsptr[5] + (DCTELEM) wsptr[3];
+		z10 = (DCTELEM) wsptr[5] - (DCTELEM) wsptr[3];
+		z11 = (DCTELEM) wsptr[1] + (DCTELEM) wsptr[7];
+		z12 = (DCTELEM) wsptr[1] - (DCTELEM) wsptr[7];
+
+		tmp7 = z11 + z13;		/* phase 5 */
+		tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); /* 2*c4 */
+
+		z5 = MULTIPLY(z10 + z12, FIX_1_847759065); /* 2*c2 */
+		tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; /* 2*(c2-c6) */
+		tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; /* -2*(c2+c6) */
+
+		tmp6 = tmp12 - tmp7;	/* phase 2 */
+		tmp5 = tmp11 - tmp6;
+		tmp4 = tmp10 + tmp5;
+
+		/* Final output stage: scale down by a factor of 8 and range-limit */
+
+		outptr[0] = range_limit[IDESCALE(tmp0 + tmp7, PASS1_BITS+3) & RANGE_MASK];
+		outptr[7] = range_limit[IDESCALE(tmp0 - tmp7, PASS1_BITS+3) & RANGE_MASK];
+		outptr[1] = range_limit[IDESCALE(tmp1 + tmp6, PASS1_BITS+3) & RANGE_MASK];
+		outptr[6] = range_limit[IDESCALE(tmp1 - tmp6, PASS1_BITS+3) & RANGE_MASK];
+		outptr[2] = range_limit[IDESCALE(tmp2 + tmp5, PASS1_BITS+3) & RANGE_MASK];
+		outptr[5] = range_limit[IDESCALE(tmp2 - tmp5, PASS1_BITS+3) & RANGE_MASK];
+		outptr[4] = range_limit[IDESCALE(tmp3 + tmp4, PASS1_BITS+3) & RANGE_MASK];
+		outptr[3] = range_limit[IDESCALE(tmp3 - tmp4, PASS1_BITS+3) & RANGE_MASK];
+
+		wsptr += DCTSIZE;		/* advance pointer to next row */
+	}
+}
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..7c9b4ed
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+#include "dct.h"
+
+int main(void) {
+	int retval;
+	int workspace[DCTSIZE_BLOCK];
+
+	retval = 0;
+	
+	fdct(workspace);
+	
+	return retval;
+}