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diff --git a/C/Ppmd.h b/C/Ppmd.h
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+/* Ppmd.h -- PPMD codec common code
+2010-03-12 : Igor Pavlov : Public domain
+This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
+
+#ifndef __PPMD_H
+#define __PPMD_H
+
+#include "Types.h"
+#include "CpuArch.h"
+
+EXTERN_C_BEGIN
+
+#ifdef MY_CPU_32BIT
+ #define PPMD_32BIT
+#endif
+
+#define PPMD_INT_BITS 7
+#define PPMD_PERIOD_BITS 7
+#define PPMD_BIN_SCALE (1 << (PPMD_INT_BITS + PPMD_PERIOD_BITS))
+
+#define PPMD_GET_MEAN_SPEC(summ, shift, round) (((summ) + (1 << ((shift) - (round)))) >> (shift))
+#define PPMD_GET_MEAN(summ) PPMD_GET_MEAN_SPEC((summ), PPMD_PERIOD_BITS, 2)
+#define PPMD_UPDATE_PROB_0(prob) ((prob) + (1 << PPMD_INT_BITS) - PPMD_GET_MEAN(prob))
+#define PPMD_UPDATE_PROB_1(prob) ((prob) - PPMD_GET_MEAN(prob))
+
+#define PPMD_N1 4
+#define PPMD_N2 4
+#define PPMD_N3 4
+#define PPMD_N4 ((128 + 3 - 1 * PPMD_N1 - 2 * PPMD_N2 - 3 * PPMD_N3) / 4)
+#define PPMD_NUM_INDEXES (PPMD_N1 + PPMD_N2 + PPMD_N3 + PPMD_N4)
+
+/* SEE-contexts for PPM-contexts with masked symbols */
+typedef struct
+{
+ UInt16 Summ; /* Freq */
+ Byte Shift; /* Speed of Freq change; low Shift is for fast change */
+ Byte Count; /* Count to next change of Shift */
+} CPpmd_See;
+
+#define Ppmd_See_Update(p) if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \
+ { (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); }
+
+typedef struct
+{
+ Byte Symbol;
+ Byte Freq;
+ UInt16 SuccessorLow;
+ UInt16 SuccessorHigh;
+} CPpmd_State;
+
+typedef
+ #ifdef PPMD_32BIT
+ CPpmd_State *
+ #else
+ UInt32
+ #endif
+ CPpmd_State_Ref;
+
+typedef
+ #ifdef PPMD_32BIT
+ void *
+ #else
+ UInt32
+ #endif
+ CPpmd_Void_Ref;
+
+typedef
+ #ifdef PPMD_32BIT
+ Byte *
+ #else
+ UInt32
+ #endif
+ CPpmd_Byte_Ref;
+
+#define PPMD_SetAllBitsIn256Bytes(p) \
+ { unsigned i; for (i = 0; i < 256 / sizeof(p[0]); i += 8) { \
+ p[i+7] = p[i+6] = p[i+5] = p[i+4] = p[i+3] = p[i+2] = p[i+1] = p[i+0] = ~(size_t)0; }}
+
+EXTERN_C_END
+
+#endif