path: root/subx/017functions.cc

//:: call

:(scenario call_imm32)
% Reg[ESP].u = 0x64;
# op  ModR/M  SIB   displacement  immediate
  e8                              a0 00 00 00  # call function offset at 0x000000a0
  # next EIP is 6
+run: call imm32 0x000000a0
+run: decrementing ESP to 0x00000060
+run: pushing value 0x00000006
+run: jumping to 0x000000a6

:(before "End Single-Byte Opcodes")
case 0xe8: {  // call imm32 relative to next EIP
  int32_t offset = imm32();
  trace(2, "run") << "call imm32 0x" << HEXWORD << offset << end();
  push(EIP);
  EIP += offset;
  trace(2, "run") << "jumping to 0x" << HEXWORD << EIP << end();
  break;
}

//:

:(scenario call_r32)
% Reg[ESP].u = 0x64;
% Reg[EBX].u = 0x000000a0;
# op  ModR/M  SIB   displacement  immediate
  ff  d3                                       # call function offset at EBX
  # next EIP is 3
+run: call to r/m32
+run: r/m32 is EBX
+run: decrementing ESP to 0x00000060
+run: pushing value 0x00000003
+run: jumping to 0x000000a3

:(before "End Op ff Subops")
case 2: {  // call function pointer at r/m32
  trace(2, "run") << "call to r/m32" << end();
  int32_t* offset = effective_address(modrm);
  push(EIP);
  EIP += *offset;
  trace(2, "run") << "jumping to 0x" << HEXWORD << EIP << end();
  break;
}

:(scenario call_mem_at_r32)
% Reg[ESP].u = 0x64;
% Reg[EBX].u = 0x10;
% write_mem_i32(0x10, 0x000000a0);
# op  ModR/M  SIB   displacement  immediate
  ff  13                                       # call function offset at *EBX
  # next EIP is 3
+run: call to r/m32
+run: effective address is 0x10 (EBX)
+run: decrementing ESP to 0x00000060
+run: pushing value 0x00000003
+run: jumping to 0x000000a3

//:: ret

:(scenario ret)
% Reg[ESP].u = 0x60;
% write_mem_i32(0x60, 0x00000010);
# op  ModR/M  SIB   displacement  immediate
  c3
+run: return
+run: popping value 0x00000010
+run: jumping to 0x00000010

:(before "End Single-Byte Opcodes")
case 0xc3: {  // return from a call
  trace(2, "run") << "return" << end();
  EIP = pop();
  trace(2, "run") << "jumping to 0x" << HEXWORD << EIP << end();
  break;
}