add ota algorithm for device

1. effective "Differential Upgrade" patch algorithm with high compression rate
2. effective recovery algorithm support recovery firmware in blocks which has low memory consumption and wear-leveling strategies, especially suitable for embeded devices with low RAM.
3. add sample ota bootloader project, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_bootloader_recovery
4. add sample application project for download firmware through http, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_application_download_through_http
5. add sample application project for download firmware through qcloud explorer console, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_application_download_through_qcloud_iot_explorer
6. an OTA markdown document is pending

components/ota/common/lzma/3rdparty/Ppmd7Enc.c

@@ -0,0 +1,187 @@
+/* Ppmd7Enc.c -- PPMdH Encoder
+2017-04-03 : Igor Pavlov : Public domain
+This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
+
+#include "Precomp.h"
+
+#include "Ppmd7.h"
+
+#define kTopValue (1 << 24)
+
+void Ppmd7z_RangeEnc_Init(CPpmd7z_RangeEnc *p)
+{
+  p->Low = 0;
+  p->Range = 0xFFFFFFFF;
+  p->Cache = 0;
+  p->CacheSize = 1;
+}
+
+static void RangeEnc_ShiftLow(CPpmd7z_RangeEnc *p)
+{
+  if ((UInt32)p->Low < (UInt32)0xFF000000 || (unsigned)(p->Low >> 32) != 0)
+  {
+    Byte temp = p->Cache;
+    do
+    {
+      IByteOut_Write(p->Stream, (Byte)(temp + (Byte)(p->Low >> 32)));
+      temp = 0xFF;
+    }
+    while (--p->CacheSize != 0);
+    p->Cache = (Byte)((UInt32)p->Low >> 24);
+  }
+  p->CacheSize++;
+  p->Low = (UInt32)p->Low << 8;
+}
+
+static void RangeEnc_Encode(CPpmd7z_RangeEnc *p, UInt32 start, UInt32 size, UInt32 total)
+{
+  p->Low += start * (p->Range /= total);
+  p->Range *= size;
+  while (p->Range < kTopValue)
+  {
+    p->Range <<= 8;
+    RangeEnc_ShiftLow(p);
+  }
+}
+
+static void RangeEnc_EncodeBit_0(CPpmd7z_RangeEnc *p, UInt32 size0)
+{
+  p->Range = (p->Range >> 14) * size0;
+  while (p->Range < kTopValue)
+  {
+    p->Range <<= 8;
+    RangeEnc_ShiftLow(p);
+  }
+}
+
+static void RangeEnc_EncodeBit_1(CPpmd7z_RangeEnc *p, UInt32 size0)
+{
+  UInt32 newBound = (p->Range >> 14) * size0;
+  p->Low += newBound;
+  p->Range -= newBound;
+  while (p->Range < kTopValue)
+  {
+    p->Range <<= 8;
+    RangeEnc_ShiftLow(p);
+  }
+}
+
+void Ppmd7z_RangeEnc_FlushData(CPpmd7z_RangeEnc *p)
+{
+  unsigned i;
+  for (i = 0; i < 5; i++)
+    RangeEnc_ShiftLow(p);
+}
+
+
+#define MASK(sym) ((signed char *)charMask)[sym]
+
+void Ppmd7_EncodeSymbol(CPpmd7 *p, CPpmd7z_RangeEnc *rc, int symbol)
+{
+  size_t charMask[256 / sizeof(size_t)];
+  if (p->MinContext->NumStats != 1)
+  {
+    CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
+    UInt32 sum;
+    unsigned i;
+    if (s->Symbol == symbol)
+    {
+      RangeEnc_Encode(rc, 0, s->Freq, p->MinContext->SummFreq);
+      p->FoundState = s;
+      Ppmd7_Update1_0(p);
+      return;
+    }
+    p->PrevSuccess = 0;
+    sum = s->Freq;
+    i = p->MinContext->NumStats - 1;
+    do
+    {
+      if ((++s)->Symbol == symbol)
+      {
+        RangeEnc_Encode(rc, sum, s->Freq, p->MinContext->SummFreq);
+        p->FoundState = s;
+        Ppmd7_Update1(p);
+        return;
+      }
+      sum += s->Freq;
+    }
+    while (--i);
+    
+    p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
+    PPMD_SetAllBitsIn256Bytes(charMask);
+    MASK(s->Symbol) = 0;
+    i = p->MinContext->NumStats - 1;
+    do { MASK((--s)->Symbol) = 0; } while (--i);
+    RangeEnc_Encode(rc, sum, p->MinContext->SummFreq - sum, p->MinContext->SummFreq);
+  }
+  else
+  {
+    UInt16 *prob = Ppmd7_GetBinSumm(p);
+    CPpmd_State *s = Ppmd7Context_OneState(p->MinContext);
+    if (s->Symbol == symbol)
+    {
+      RangeEnc_EncodeBit_0(rc, *prob);
+      *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
+      p->FoundState = s;
+      Ppmd7_UpdateBin(p);
+      return;
+    }
+    else
+    {
+      RangeEnc_EncodeBit_1(rc, *prob);
+      *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
+      p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
+      PPMD_SetAllBitsIn256Bytes(charMask);
+      MASK(s->Symbol) = 0;
+      p->PrevSuccess = 0;
+    }
+  }
+  for (;;)
+  {
+    UInt32 escFreq;
+    CPpmd_See *see;
+    CPpmd_State *s;
+    UInt32 sum;
+    unsigned i, numMasked = p->MinContext->NumStats;
+    do
+    {
+      p->OrderFall++;
+      if (!p->MinContext->Suffix)
+        return; /* EndMarker (symbol = -1) */
+      p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
+    }
+    while (p->MinContext->NumStats == numMasked);
+    
+    see = Ppmd7_MakeEscFreq(p, numMasked, &escFreq);
+    s = Ppmd7_GetStats(p, p->MinContext);
+    sum = 0;
+    i = p->MinContext->NumStats;
+    do
+    {
+      int cur = s->Symbol;
+      if (cur == symbol)
+      {
+        UInt32 low = sum;
+        CPpmd_State *s1 = s;
+        do
+        {
+          sum += (s->Freq & (int)(MASK(s->Symbol)));
+          s++;
+        }
+        while (--i);
+        RangeEnc_Encode(rc, low, s1->Freq, sum + escFreq);
+        Ppmd_See_Update(see);
+        p->FoundState = s1;
+        Ppmd7_Update2(p);
+        return;
+      }
+      sum += (s->Freq & (int)(MASK(cur)));
+      MASK(cur) = 0;
+      s++;
+    }
+    while (--i);
+    
+    RangeEnc_Encode(rc, sum, escFreq, sum + escFreq);
+    see->Summ = (UInt16)(see->Summ + sum + escFreq);
+  }
+}