/* Disassembly display.

   Copyright (C) 1998-2020 Free Software Foundation, Inc.

   Contributed by Hewlett-Packard Company.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "arch-utils.h"
#include "symtab.h"
#include "breakpoint.h"
#include "frame.h"
#include "value.h"
#include "source.h"
#include "disasm.h"
#include "tui/tui.h"
#include "tui/tui-command.h"
#include "tui/tui-data.h"
#include "tui/tui-win.h"
#include "tui/tui-layout.h"
#include "tui/tui-winsource.h"
#include "tui/tui-stack.h"
#include "tui/tui-file.h"
#include "tui/tui-disasm.h"
#include "tui/tui-source.h"
#include "progspace.h"
#include "objfiles.h"
#include "cli/cli-style.h"

#include "gdb_curses.h"

struct tui_asm_line
{
  CORE_ADDR addr;
  std::string addr_string;
  size_t addr_size;
  std::string insn;
};

/* Helper function to find the number of characters in STR, skipping
   any ANSI escape sequences.  */
static size_t
len_without_escapes (const std::string &str)
{
  size_t len = 0;
  const char *ptr = str.c_str ();
  char c;

  while ((c = *ptr++) != '\0')
    {
      if (c == '\033')
	{
	  ui_file_style style;
	  size_t n_read;
	  if (style.parse (ptr, &n_read))
	    ptr += n_read;
	  else
	    {
	      /* Shouldn't happen, but just skip the ESC if it somehow
		 does.  */
	      ++ptr;
	    }
	}
      else
	++len;
    }
  return len;
}

/* Function to set the disassembly window's content.
   Disassemble count lines starting at pc.
   Return address of the count'th instruction after pc.  */
static CORE_ADDR
tui_disassemble (struct gdbarch *gdbarch,
		 std::vector<tui_asm_line> &asm_lines,
		 CORE_ADDR pc, int pos, int count,
		 size_t *addr_size = nullptr)
{
  bool term_out = source_styling && gdb_stdout->can_emit_style_escape ();
  string_file gdb_dis_out (term_out);

  /* Now construct each line.  */
  for (int i = 0; i < count; ++i)
    {
      print_address (gdbarch, pc, &gdb_dis_out);
      asm_lines[pos + i].addr = pc;
      asm_lines[pos + i].addr_string = std::move (gdb_dis_out.string ());

      gdb_dis_out.clear ();

      if (addr_size != nullptr)
	{
	  size_t new_size;

	  if (term_out)
	    new_size = len_without_escapes (asm_lines[pos + i].addr_string);
	  else
	    new_size = asm_lines[pos + i].addr_string.size ();
	  *addr_size = std::max (*addr_size, new_size);
	  asm_lines[pos + i].addr_size = new_size;
	}

      pc = pc + gdb_print_insn (gdbarch, pc, &gdb_dis_out, NULL);

      asm_lines[pos + i].insn = std::move (gdb_dis_out.string ());

      /* Reset the buffer to empty.  */
      gdb_dis_out.clear ();
    }
  return pc;
}

/* Find the disassembly address that corresponds to FROM lines above
   or below the PC.  Variable sized instructions are taken into
   account by the algorithm.  */
static CORE_ADDR
tui_find_disassembly_address (struct gdbarch *gdbarch, CORE_ADDR pc, int from)
{
  CORE_ADDR new_low;
  int max_lines;

  max_lines = (from > 0) ? from : - from;
  if (max_lines <= 1)
    return pc;

  std::vector<tui_asm_line> asm_lines (max_lines);

  new_low = pc;
  if (from > 0)
    {
      tui_disassemble (gdbarch, asm_lines, pc, 0, max_lines);
      new_low = asm_lines[max_lines - 1].addr;
    }
  else
    {
      CORE_ADDR last_addr;
      int pos;
      struct bound_minimal_symbol msymbol;

      /* Find backward an address which is a symbol and for which
         disassembling from that address will fill completely the
         window.  */
      pos = max_lines - 1;
      do {
         new_low -= 1 * max_lines;
         msymbol = lookup_minimal_symbol_by_pc_section (new_low, 0);

         if (msymbol.minsym)
            new_low = BMSYMBOL_VALUE_ADDRESS (msymbol);
         else
            new_low += 1 * max_lines;

         tui_disassemble (gdbarch, asm_lines, new_low, 0, max_lines);
         last_addr = asm_lines[pos].addr;
      } while (last_addr > pc && msymbol.minsym);

      /* Scan forward disassembling one instruction at a time until
         the last visible instruction of the window matches the pc.
         We keep the disassembled instructions in the 'lines' window
         and shift it downward (increasing its addresses).  */
      if (last_addr < pc)
        do
          {
            CORE_ADDR next_addr;

            pos++;
            if (pos >= max_lines)
              pos = 0;

            next_addr = tui_disassemble (gdbarch, asm_lines,
					 last_addr, pos, 1);

            /* If there are some problems while disassembling exit.  */
            if (next_addr <= last_addr)
              break;
            last_addr = next_addr;
          } while (last_addr <= pc);
      pos++;
      if (pos >= max_lines)
         pos = 0;
      new_low = asm_lines[pos].addr;
    }
  return new_low;
}

/* Function to set the disassembly window's content.  */
bool
tui_disasm_window::set_contents (struct gdbarch *arch,
				 const struct symtab_and_line &sal)
{
  int i;
  int offset = horizontal_offset;
  int max_lines, line_width;
  CORE_ADDR cur_pc;
  struct tui_locator_window *locator = tui_locator_win_info_ptr ();
  int tab_len = tui_tab_width;
  int insn_pos;

  CORE_ADDR pc = sal.pc;
  if (pc == 0)
    return false;

  gdbarch = arch;
  start_line_or_addr.loa = LOA_ADDRESS;
  start_line_or_addr.u.addr = pc;
  cur_pc = locator->addr;

  /* Window size, excluding highlight box.  */
  max_lines = height - 2;
  line_width = width - TUI_EXECINFO_SIZE - 2;

  /* Get temporary table that will hold all strings (addr & insn).  */
  std::vector<tui_asm_line> asm_lines (max_lines);
  size_t addr_size = 0;
  tui_disassemble (gdbarch, asm_lines, pc, 0, max_lines, &addr_size);

  /* Align instructions to the same column.  */
  insn_pos = (1 + (addr_size / tab_len)) * tab_len;

  /* Now construct each line.  */
  content.resize (max_lines);
  for (i = 0; i < max_lines; i++)
    {
      tui_source_element *src = &content[i];

      std::string line
	= (asm_lines[i].addr_string
	   + n_spaces (insn_pos - asm_lines[i].addr_size)
	   + asm_lines[i].insn);

      const char *ptr = line.c_str ();
      src->line = tui_copy_source_line (&ptr, -1, offset, line_width, 0);

      src->line_or_addr.loa = LOA_ADDRESS;
      src->line_or_addr.u.addr = asm_lines[i].addr;
      src->is_exec_point = asm_lines[i].addr == cur_pc;
    }
  return true;
}


void
tui_get_begin_asm_address (struct gdbarch **gdbarch_p, CORE_ADDR *addr_p)
{
  struct tui_locator_window *locator;
  struct gdbarch *gdbarch = get_current_arch ();
  CORE_ADDR addr = 0;

  locator = tui_locator_win_info_ptr ();

  if (locator->addr == 0)
    {
      if (have_full_symbols () || have_partial_symbols ())
	{
	  set_default_source_symtab_and_line ();
	  struct symtab_and_line sal = get_current_source_symtab_and_line ();

	  if (sal.symtab != nullptr)
	    find_line_pc (sal.symtab, sal.line, &addr);
	}

      if (addr == 0)
	{
	  struct bound_minimal_symbol main_symbol
	    = lookup_minimal_symbol (main_name (), nullptr, nullptr);
	  if (main_symbol.minsym != nullptr)
	    addr = BMSYMBOL_VALUE_ADDRESS (main_symbol);
	}
    }
  else				/* The target is executing.  */
    {
      gdbarch = locator->gdbarch;
      addr = locator->addr;
    }

  *gdbarch_p = gdbarch;
  *addr_p = addr;
}

/* Determine what the low address will be to display in the TUI's
   disassembly window.  This may or may not be the same as the low
   address input.  */
CORE_ADDR
tui_get_low_disassembly_address (struct gdbarch *gdbarch,
				 CORE_ADDR low, CORE_ADDR pc)
{
  int pos;

  /* Determine where to start the disassembly so that the pc is about
     in the middle of the viewport.  */
  if (tui_win_list[DISASSEM_WIN] != NULL)
    pos = tui_win_list[DISASSEM_WIN]->height;
  else if (TUI_CMD_WIN == NULL)
    pos = tui_term_height () / 2 - 2;
  else
    pos = tui_term_height () - TUI_CMD_WIN->height - 2;
  pos = (pos - 2) / 2;

  pc = tui_find_disassembly_address (gdbarch, pc, -pos);

  if (pc < low)
    pc = low;
  return pc;
}

/* Scroll the disassembly forward or backward vertically.  */
void
tui_disasm_window::do_scroll_vertical (int num_to_scroll)
{
  if (!content.empty ())
    {
      CORE_ADDR pc;

      pc = start_line_or_addr.u.addr;
      if (num_to_scroll >= 0)
	num_to_scroll++;
      else
	--num_to_scroll;

      symtab_and_line sal {};
      sal.pspace = current_program_space;
      sal.pc = tui_find_disassembly_address (gdbarch, pc, num_to_scroll);
      update_source_window_as_is (gdbarch, sal);
    }
}

bool
tui_disasm_window::location_matches_p (struct bp_location *loc, int line_no)
{
  return (content[line_no].line_or_addr.loa == LOA_ADDRESS
	  && content[line_no].line_or_addr.u.addr == loc->address);
}

bool
tui_disasm_window::addr_is_displayed (CORE_ADDR addr) const
{
  if (content.size () < SCROLL_THRESHOLD)
    return false;

  for (size_t i = 0; i < content.size () - SCROLL_THRESHOLD; ++i)
    {
      if (content[i].line_or_addr.loa == LOA_ADDRESS
	  && content[i].line_or_addr.u.addr == addr)
	return true;
    }

  return false;
}

void
tui_disasm_window::maybe_update (struct frame_info *fi, symtab_and_line sal)
{
  CORE_ADDR low;

  struct gdbarch *frame_arch = get_frame_arch (fi);

  if (find_pc_partial_function (sal.pc, NULL, &low, NULL) == 0)
    {
      /* There is no symbol available for current PC.  There is no
	 safe way how to "disassemble backwards".  */
      low = sal.pc;
    }
  else
    low = tui_get_low_disassembly_address (frame_arch, low, sal.pc);

  struct tui_line_or_address a;

  a.loa = LOA_ADDRESS;
  a.u.addr = low;
  if (!addr_is_displayed (sal.pc))
    {
      sal.pc = low;
      update_source_window (frame_arch, sal);
    }
  else
    {
      a.u.addr = sal.pc;
      set_is_exec_point_at (a);
    }
}