/* Capstone Disassembly Engine */

/* By Rot127 <unisono@quyllur.org>, 2023 */

#include "MCInstPrinter.h"

#include "cs_priv.h"

#include <capstone/platform.h>

extern bool ARM_getFeatureBits(unsigned int mode, unsigned int feature);

extern bool PPC_getFeatureBits(unsigned int mode, unsigned int feature);

extern bool AArch64_getFeatureBits(unsigned int mode, unsigned int feature);

static bool testFeatureBits(const MCInst *MI, uint32_t Value)

{

  assert(MI && MI->csh);

  switch (MI->csh->arch) {

  default:

    assert(0 && "Not implemented for current arch.");

    return false;

#ifdef CAPSTONE_HAS_ARM

  case CS_ARCH_ARM:

    return ARM_getFeatureBits(MI->csh->mode, Value);

#endif

#ifdef CAPSTONE_HAS_POWERPC

  case CS_ARCH_PPC:

    return PPC_getFeatureBits(MI->csh->mode, Value);

#endif

#ifdef CAPSTONE_HAS_AARCH64

  case CS_ARCH_AARCH64:

    return AArch64_getFeatureBits(MI->csh->mode, Value);

#endif

  }

}

static bool matchAliasCondition(MCInst *MI, const MCRegisterInfo *MRI,

                unsigned *OpIdx, const AliasMatchingData *M,

                const AliasPatternCond *C,

                bool *OrPredicateResult)

{

  // Feature tests are special, they don't consume operands.

  if (C->Kind == AliasPatternCond_K_Feature)

    return testFeatureBits(MI, C->Value);

  if (C->Kind == AliasPatternCond_K_NegFeature)

    return !testFeatureBits(MI, C->Value);

  // For feature tests where just one feature is required in a list, set the

  // predicate result bit to whether the expression will return true, and only

  // return the real result at the end of list marker.

  if (C->Kind == AliasPatternCond_K_OrFeature) {

    *OrPredicateResult |= testFeatureBits(MI, C->Value);

    return true;

  }

  if (C->Kind == AliasPatternCond_K_OrNegFeature) {

    *OrPredicateResult |= !(testFeatureBits(MI, C->Value));

    return true;

  }

  if (C->Kind == AliasPatternCond_K_EndOrFeatures) {

    bool Res = *OrPredicateResult;

    *OrPredicateResult = false;

    return Res;

  }

  // Get and consume an operand.

  MCOperand *Opnd = MCInst_getOperand(MI, *OpIdx);

  ++(*OpIdx);

  // Check the specific condition for the operand.

  switch (C->Kind) {

  default:

    assert(0 && "invalid kind");

  case AliasPatternCond_K_Imm:

    // Operand must be a specific immediate.

    return MCOperand_isImm(Opnd) &&

         MCOperand_getImm(Opnd) == (int32_t)C->Value;

  case AliasPatternCond_K_Reg:

    // Operand must be a specific register.

    return MCOperand_isReg(Opnd) && MCOperand_getReg(Opnd) == C->Value;

  case AliasPatternCond_K_TiedReg:

    // Operand must match the register of another operand.

    return MCOperand_isReg(Opnd) &&

         MCOperand_getReg(Opnd) ==

           MCOperand_getReg(MCInst_getOperand(MI, C->Value));

  case AliasPatternCond_K_RegClass:

    // Operand must be a register in this class. Value is a register class

    // id.

    return MCOperand_isReg(Opnd) &&

         MCRegisterClass_contains(

           MCRegisterInfo_getRegClass(MRI, C->Value),

           MCOperand_getReg(Opnd));

  case AliasPatternCond_K_Custom:

    // Operand must match some custom criteria.

    assert(M->ValidateMCOperand && "A custom validator should be set but isn't.");

    return M->ValidateMCOperand(Opnd, C->Value);

  case AliasPatternCond_K_Ignore:

    // Operand can be anything.

    return true;

  case AliasPatternCond_K_Feature:

  case AliasPatternCond_K_NegFeature:

  case AliasPatternCond_K_OrFeature:

  case AliasPatternCond_K_OrNegFeature:

  case AliasPatternCond_K_EndOrFeatures:

    assert(0 && "handled earlier");

  }

  return false;

}

/// Check if PatternsForOpcode is all zero.

static inline bool validOpToPatter(const PatternsForOpcode *P)

{

  return !(P->Opcode == 0 && P->PatternStart == 0 && P->NumPatterns == 0);

}

const char *matchAliasPatterns(MCInst *MI, const AliasMatchingData *M)

{

  // TODO Rewrite to C

  // auto It = lower_bound(M.OpToPatterns, MI->getOpcode(),

  //                       [](const PatternsForOpcode &L, unsigned Opcode) {

  //                         return L.Opcode < Opcode;

  //                       });

  // if (It == M.OpToPatterns.end() || It->Opcode != MI->getOpcode())

  //   return nullptr;

  // Binary search by opcode. Return false if there are no aliases for this

  // opcode.

  unsigned MIOpcode = MI->Opcode;

  size_t i = 0;

  uint32_t PatternOpcode = M->OpToPatterns[i].Opcode;

  while (PatternOpcode < MIOpcode && validOpToPatter(&M->OpToPatterns[i]))

    PatternOpcode = M->OpToPatterns[++i].Opcode;

  if (PatternOpcode != MI->Opcode || !validOpToPatter(&M->OpToPatterns[i]))

    return NULL;

  // // Try all patterns for this opcode.

  uint32_t AsmStrOffset = ~0U;

  const AliasPattern *Patterns = M->Patterns + M->OpToPatterns[i].PatternStart;

  for (const AliasPattern *P = Patterns;

    P != Patterns + M->OpToPatterns[i].NumPatterns; ++P) {

    // Check operand count first.

    if (MCInst_getNumOperands(MI) != P->NumOperands)

      return NULL;

    // Test all conditions for this pattern.

    const AliasPatternCond *Conds = M->PatternConds + P->AliasCondStart;

    unsigned OpIdx = 0;

    bool OrPredicateResult = false;

    bool allMatch = true;

    for (const AliasPatternCond *C = Conds; C != Conds + P->NumConds; ++C) {

      if (!matchAliasCondition(MI, MI->MRI, &OpIdx, M, C, &OrPredicateResult)) {

        allMatch = false;

        break;

      }

    }

    if (allMatch) {

      AsmStrOffset = P->AsmStrOffset;

      break;

    }

  }

  // If no alias matched, don't print an alias.

  if (AsmStrOffset == ~0U)

    return NULL;

  // Go to offset AsmStrOffset and use the null terminated string there. The

  // offset should point to the beginning of an alias string, so it should

  // either be zero or be preceded by a null byte.

  return M->AsmStrings + AsmStrOffset;

}

// TODO Add functionality to toggle the flag.

bool getUseMarkup(void) { return false; }

/// Utility functions to make adding mark ups simpler.

const char *markup(const char *s)

{

  static const char *no_markup = "";

  if (getUseMarkup())

    return s;

  else

    return no_markup;

}

// binary search for encoding in IndexType array

// return -1 if not found, or index if found

unsigned int binsearch_IndexTypeEncoding(const struct IndexType *index, size_t size, uint16_t encoding)

{

  // binary searching since the index is sorted in encoding order

  size_t left, right, m;

  right = size - 1;

  if (encoding < index[0].encoding || encoding > index[right].encoding)

    // not found

    return -1;

  left = 0;

  while(left <= right) {

    m = (left + right) / 2;

    if (encoding == index[m].encoding) {

      // LLVM actually uses lower_bound for the index table search

      // Here we need to check if a previous entry is of the same encoding

      // and return the first one.

      while (m > 0 && encoding == index[m - 1].encoding)

        --m;

      return m;

    }

    if (encoding < index[m].encoding)

      right = m - 1;

    else

      left = m + 1;

  }

  // not found

  return -1;

}

// binary search for encoding in IndexTypeStr array

// return -1 if not found, or index if found

unsigned int binsearch_IndexTypeStrEncoding(const struct IndexTypeStr *index, size_t size, const char *name)

{

  // binary searching since the index is sorted in encoding order

  size_t left, right, m;

  right = size - 1;

  size_t str_left_cmp = strcmp(name, index[0].name);

  size_t str_right_cmp = strcmp(name, index[right].name);

  if (str_left_cmp < 0 || str_right_cmp > 0)

    // not found

    return -1;

  left = 0;

  while(left <= right) {

    m = (left + right) / 2;

    if (strcmp(name, index[m].name) == 0) {

      // LLVM actually uses lower_bound for the index table search

      // Here we need to check if a previous entry is of the same encoding

      // and return the first one.

      while (m > 0 && (strcmp(name, index[m - 1].name) == 0))

        --m;

      return m;

    }

    if (strcmp(name, index[m].name) < 0)

      right = m - 1;

    else

      left = m + 1;

  }

  // not found

  return -1;

}