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+/*
+ * jdct.h
+ *
+ * This file was part of the Independent JPEG Group's software:
+ * Copyright (C) 1994-1996, Thomas G. Lane.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2015, D. R. Commander.
+ * For conditions of distribution and use, see the accompanying README.ijg
+ * file.
+ *
+ * This include file contains common declarations for the forward and
+ * inverse DCT modules. These declarations are private to the DCT managers
+ * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.
+ * The individual DCT algorithms are kept in separate files to ease
+ * machine-dependent tuning (e.g., assembly coding).
+ */
+
+
+/*
+ * A forward DCT routine is given a pointer to a work area of type DCTELEM[];
+ * the DCT is to be performed in-place in that buffer. Type DCTELEM is int
+ * for 8-bit samples, JLONG for 12-bit samples. (NOTE: Floating-point DCT
+ * implementations use an array of type FAST_FLOAT, instead.)
+ * The DCT inputs are expected to be signed (range +-CENTERJSAMPLE).
+ * The DCT outputs are returned scaled up by a factor of 8; they therefore
+ * have a range of +-8K for 8-bit data, +-128K for 12-bit data. This
+ * convention improves accuracy in integer implementations and saves some
+ * work in floating-point ones.
+ * Quantization of the output coefficients is done by jcdctmgr.c. This
+ * step requires an unsigned type and also one with twice the bits.
+ */
+
+#if BITS_IN_JSAMPLE == 8
+#ifndef WITH_SIMD
+typedef int DCTELEM; /* 16 or 32 bits is fine */
+typedef unsigned int UDCTELEM;
+typedef unsigned long long UDCTELEM2;
+#else
+typedef short DCTELEM; /* prefer 16 bit with SIMD for parellelism */
+typedef unsigned short UDCTELEM;
+typedef unsigned int UDCTELEM2;
+#endif
+#else
+typedef JLONG DCTELEM; /* must have 32 bits */
+typedef unsigned long long UDCTELEM2;
+#endif
+
+
+/*
+ * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
+ * to an output sample array. The routine must dequantize the input data as
+ * well as perform the IDCT; for dequantization, it uses the multiplier table
+ * pointed to by compptr->dct_table. The output data is to be placed into the
+ * sample array starting at a specified column. (Any row offset needed will
+ * be applied to the array pointer before it is passed to the IDCT code.)
+ * Note that the number of samples emitted by the IDCT routine is
+ * DCT_scaled_size * DCT_scaled_size.
+ */
+
+/* typedef inverse_DCT_method_ptr is declared in jpegint.h */
+
+/*
+ * Each IDCT routine has its own ideas about the best dct_table element type.
+ */
+
+typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */
+#if BITS_IN_JSAMPLE == 8
+typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */
+#define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
+#else
+typedef JLONG IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */
+#define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
+#endif
+typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
+
+
+/*
+ * Each IDCT routine is responsible for range-limiting its results and
+ * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could
+ * be quite far out of range if the input data is corrupt, so a bulletproof
+ * range-limiting step is required. We use a mask-and-table-lookup method
+ * to do the combined operations quickly. See the comments with
+ * prepare_range_limit_table (in jdmaster.c) for more info.
+ */
+
+#define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
+
+#define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
+
+
+/* Extern declarations for the forward and inverse DCT routines. */
+
+EXTERN(void) jpeg_fdct_islow(DCTELEM *data);
+EXTERN(void) jpeg_fdct_ifast(DCTELEM *data);
+EXTERN(void) jpeg_fdct_float(FAST_FLOAT *data);
+
+EXTERN(void) jpeg_idct_islow(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_ifast(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_float(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_7x7(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_6x6(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_5x5(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_4x4(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_3x3(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_2x2(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_1x1(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_9x9(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_10x10(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_11x11(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_12x12(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_13x13(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_14x14(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_15x15(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+EXTERN(void) jpeg_idct_16x16(j_decompress_ptr cinfo,
+ jpeg_component_info *compptr, JCOEFPTR coef_block,
+ JSAMPARRAY output_buf, JDIMENSION output_col);
+
+
+/*
+ * Macros for handling fixed-point arithmetic; these are used by many
+ * but not all of the DCT/IDCT modules.
+ *
+ * All values are expected to be of type JLONG.
+ * Fractional constants are scaled left by CONST_BITS bits.
+ * CONST_BITS is defined within each module using these macros,
+ * and may differ from one module to the next.
+ */
+
+#define ONE ((JLONG)1)
+#define CONST_SCALE (ONE << CONST_BITS)
+
+/* Convert a positive real constant to an integer scaled by CONST_SCALE.
+ * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
+ * thus causing a lot of useless floating-point operations at run time.
+ */
+
+#define FIX(x) ((JLONG)((x) * CONST_SCALE + 0.5))
+
+/* Descale and correctly round a JLONG value that's scaled by N bits.
+ * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
+ * the fudge factor is correct for either sign of X.
+ */
+
+#define DESCALE(x, n) RIGHT_SHIFT((x) + (ONE << ((n) - 1)), n)
+
+/* Multiply a JLONG variable by a JLONG constant to yield a JLONG result.
+ * This macro is used only when the two inputs will actually be no more than
+ * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
+ * full 32x32 multiply. This provides a useful speedup on many machines.
+ * Unfortunately there is no way to specify a 16x16->32 multiply portably
+ * in C, but some C compilers will do the right thing if you provide the
+ * correct combination of casts.
+ */
+
+#ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
+#define MULTIPLY16C16(var, const) (((INT16)(var)) * ((INT16)(const)))
+#endif
+#ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
+#define MULTIPLY16C16(var, const) (((INT16)(var)) * ((JLONG)(const)))
+#endif
+
+#ifndef MULTIPLY16C16 /* default definition */
+#define MULTIPLY16C16(var, const) ((var) * (const))
+#endif
+
+/* Same except both inputs are variables. */
+
+#ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
+#define MULTIPLY16V16(var1, var2) (((INT16)(var1)) * ((INT16)(var2)))
+#endif
+
+#ifndef MULTIPLY16V16 /* default definition */
+#define MULTIPLY16V16(var1, var2) ((var1) * (var2))
+#endif