/* s390-dis.c -- Disassemble S390 instructions
  Copyright (C) 2000-2024 Free Software Foundation, Inc.
  Contributed by Martin Schwidefsky ([email protected]).

  This file is part of the GNU opcodes library.

  This library 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, or (at your option)
  any later version.

  It 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 file; see the file COPYING.  If not, write to the
  Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
  MA 02110-1301, USA.  */

#include "sysdep.h"
#include <stdio.h>
#include "ansidecl.h"
#include "disassemble.h"
#include "opintl.h"
#include "opcode/s390.h"
#include "libiberty.h"
#include "dis-asm.h"

static int opc_index[256];
static int current_arch_mask = 0;
static int option_use_insn_len_bits_p = 0;
static int option_print_insn_desc = 0;

typedef struct
{
 const char *name;
 const char *description;
} s390_options_t;

static const s390_options_t options[] =
{
 { "esa" ,       N_("Disassemble in ESA architecture mode") },
 { "zarch",      N_("Disassemble in z/Architecture mode") },
 { "insnlength", N_("Print unknown instructions according to "
                    "length from first two bits") },
 { "insndesc",   N_("Print instruction description as comment") },
};

/* Set up index table for first opcode byte.  */

void
disassemble_init_s390 (struct disassemble_info *info)
{
 int i;
 const char *p;

 memset (opc_index, 0, sizeof (opc_index));

 /* Reverse order, such that each opc_index ends up pointing to the
    first matching entry instead of the last.  */
 for (i = s390_num_opcodes; i--; )
   opc_index[s390_opcodes[i].opcode[0]] = i;

 current_arch_mask = 1 << S390_OPCODE_ZARCH;
 option_use_insn_len_bits_p = 0;
 option_print_insn_desc = 0;

 for (p = info->disassembler_options; p != NULL; )
   {
     if (startswith (p, "esa"))
       current_arch_mask = 1 << S390_OPCODE_ESA;
     else if (startswith (p, "zarch"))
       current_arch_mask = 1 << S390_OPCODE_ZARCH;
     else if (startswith (p, "insnlength"))
       option_use_insn_len_bits_p = 1;
     else if (startswith (p, "insndesc"))
       option_print_insn_desc = 1;
     else
       /* xgettext:c-format */
       opcodes_error_handler (_("unknown S/390 disassembler option: %s"), p);

     p = strchr (p, ',');
     if (p != NULL)
       p++;
   }
}

/* Derive the length of an instruction from its first byte.  */

static inline int
s390_insn_length (const bfd_byte *buffer)
{
 /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6.  */
 return ((buffer[0] >> 6) + 3) & ~1U;
}

/* Match the instruction in BUFFER against the given OPCODE, excluding
  the first byte.  */

static inline int
s390_insn_matches_opcode (const bfd_byte *buffer,
                         const struct s390_opcode *opcode)
{
 return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
   && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
   && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
   && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
   && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
}

union operand_value
{
 int i;
 unsigned int u;
};

/* Extracts an operand value from an instruction.  */
/* We do not perform the shift operation for larl-type address
  operands here since that would lead to an overflow of the 32 bit
  integer value.  Instead the shift operation is done when printing
  the operand.  */

static inline union operand_value
s390_extract_operand (const bfd_byte *insn,
                     const struct s390_operand *operand)
{
 union operand_value ret;
 unsigned int val;
 int bits;
 const bfd_byte *orig_insn = insn;

 /* Extract fragments of the operand byte for byte.  */
 insn += operand->shift / 8;
 bits = (operand->shift & 7) + operand->bits;
 val = 0;
 do
   {
     val <<= 8;
     val |= (unsigned int) *insn++;
     bits -= 8;
   }
 while (bits > 0);
 val >>= -bits;
 val &= ((1U << (operand->bits - 1)) << 1) - 1;

 /* Check for special long displacement case.  */
 if (operand->bits == 20 && operand->shift == 20)
   val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;

 /* Sign extend value if the operand is signed or pc relative.  Avoid
    integer overflows.  */
 if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
   {
     unsigned int m = 1U << (operand->bits - 1);

     if (val >= m)
       ret.i = (int) (val - m) - 1 - (int) (m - 1U);
     else
       ret.i = (int) val;
   }
 else if (operand->flags & S390_OPERAND_LENGTH)
   /* Length x in an instruction has real length x + 1.  */
   ret.u = val + 1;

 else if (operand->flags & S390_OPERAND_VR)
   {
     /* Extract the extra bits for a vector register operand stored
        in the RXB field.  */
     unsigned vr = operand->shift == 32 ? 3
       : (unsigned) operand->shift / 4 - 2;

     ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
   }
 else
   ret.u = val;

 return ret;
}

/* Print the S390 instruction in BUFFER, assuming that it matches the
  given OPCODE.  */

static void
s390_print_insn_with_opcode (bfd_vma memaddr,
                            struct disassemble_info *info,
                            const bfd_byte *buffer,
                            const struct s390_opcode *opcode)
{
 const unsigned char *opindex;
 char separator;

 /* Mnemonic.  */
 info->fprintf_styled_func (info->stream, dis_style_mnemonic,
                            "%s", opcode->name);

 /* Operands.  */
 separator = '\t';
 for (opindex = opcode->operands; *opindex != 0; opindex++)
   {
     const struct s390_operand *operand = s390_operands + *opindex;
     union operand_value val = s390_extract_operand (buffer, operand);
     unsigned long flags = operand->flags;

     if ((flags & S390_OPERAND_INDEX) && val.u == 0)
       continue;
     if ((flags & S390_OPERAND_BASE) &&
         val.u == 0 && separator == '(')
       {
         separator = ',';
         continue;
       }

     /* For instructions with a last optional operand don't print it
        if zero.  */
     if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))
         && val.u == 0
         && opindex[1] == 0)
       break;

     if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)
         && val.u == 0 && opindex[1] != 0 && opindex[2] == 0)
       {
         union operand_value next_op_val =
           s390_extract_operand (buffer, s390_operands + opindex[1]);
         if (next_op_val.u == 0)
           break;
       }

     if (flags & S390_OPERAND_GPR)
       {
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->fprintf_styled_func (info->stream, dis_style_register,
                                    "%%r%u", val.u);
       }
     else if (flags & S390_OPERAND_FPR)
       {
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->fprintf_styled_func (info->stream, dis_style_register,
                                    "%%f%u", val.u);
       }
     else if (flags & S390_OPERAND_VR)
       {
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->fprintf_styled_func (info->stream, dis_style_register,
                                    "%%v%i", val.u);
       }
     else if (flags & S390_OPERAND_AR)
       {
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->fprintf_styled_func (info->stream, dis_style_register,
                                    "%%a%u", val.u);
       }
     else if (flags & S390_OPERAND_CR)
       {
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->fprintf_styled_func (info->stream, dis_style_register,
                                    "%%c%u", val.u);
       }
     else if (flags & S390_OPERAND_PCREL)
       {
         bfd_vma target = memaddr + val.i + val.i;

         /* Provide info for jump visualization.  May be evaluated by p_a_f().  */
         info->target = target;

         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         info->print_address_func (target, info);
       }
     else if (flags & S390_OPERAND_SIGNED)
       {
         enum disassembler_style style;

         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         style = ((flags & S390_OPERAND_DISP)
                  ? dis_style_address_offset : dis_style_immediate);
         info->fprintf_styled_func (info->stream, style, "%i", val.i);
       }
     else
       {
         enum disassembler_style style;

         if (flags & S390_OPERAND_OR1)
           val.u &= ~1;
         if (flags & S390_OPERAND_OR2)
           val.u &= ~2;
         if (flags & S390_OPERAND_OR8)
           val.u &= ~8;

         if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
             && val.u == 0
             && opindex[1] == 0)
           break;
         info->fprintf_styled_func (info->stream, dis_style_text,
                                    "%c", separator);
         style = ((flags & S390_OPERAND_DISP)
                  ? dis_style_address_offset : dis_style_immediate);
         info->fprintf_styled_func (info->stream, style, "%u", val.u);
       }

     if (flags & S390_OPERAND_DISP)
       separator = '(';
     else if (flags & S390_OPERAND_BASE)
       {
         info->fprintf_styled_func (info->stream, dis_style_text, ")");
         separator = ',';
       }
     else
       separator = ',';
   }

 /* Optional: instruction name.  */
 if (option_print_insn_desc && opcode->description
     && opcode->description[0] != '\0')
   info->fprintf_styled_func (info->stream, dis_style_comment_start, "\t# %s",
                              opcode->description);
}

/* Check whether opcode A's mask is more specific than that of B.  */

static int
opcode_mask_more_specific (const struct s390_opcode *a,
                          const struct s390_opcode *b)
{
 return (((int) a->mask[0] + a->mask[1] + a->mask[2]
          + a->mask[3] + a->mask[4] + a->mask[5])
         > ((int) b->mask[0] + b->mask[1] + b->mask[2]
            + b->mask[3] + b->mask[4] + b->mask[5]));
}

/* Print a S390 instruction.  */

int
print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
{
 bfd_byte buffer[6];
 const struct s390_opcode *opcode = NULL;
 unsigned int value;
 int status, opsize, bufsize, bytes_to_dump, i;

 /* The output looks better if we put 6 bytes on a line.  */
 info->bytes_per_line = 6;

 /* Set some defaults for the insn info.  */
 info->insn_info_valid    = 0;
 info->branch_delay_insns = 0;
 info->data_size          = 0;
 info->insn_type          = dis_nonbranch;
 info->target             = 0;
 info->target2            = 0;

 /* Every S390 instruction is max 6 bytes long.  */
 memset (buffer, 0, 6);
 status = info->read_memory_func (memaddr, buffer, 6, info);
 if (status != 0)
   {
     for (bufsize = 0; bufsize < 6; bufsize++)
       if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
         break;
     if (bufsize <= 0)
       {
         info->memory_error_func (status, memaddr, info);
         return -1;
       }
     opsize = s390_insn_length (buffer);
     status = opsize > bufsize;
   }
 else
   {
     bufsize = 6;
     opsize = s390_insn_length (buffer);
   }

 if (status == 0)
   {
     const struct s390_opcode *op;

     /* Find the "best match" in the opcode table.  */
     for (op = s390_opcodes + opc_index[buffer[0]];
          op != s390_opcodes + s390_num_opcodes
            && op->opcode[0] == buffer[0];
          op++)
       {
         if ((op->modes & current_arch_mask)
             && s390_insn_matches_opcode (buffer, op)
             && (opcode == NULL
                 || opcode_mask_more_specific (op, opcode)))
           opcode = op;
       }

     if (opcode != NULL)
       {
         /* Provide info for jump visualization.  Must be done before print.  */
         switch (opcode->flags & S390_INSTR_FLAG_CLASS_MASK)
           {
           case S390_INSTR_FLAGS_CLASS_JUMP:
             info->insn_type = dis_branch;
             break;
           case S390_INSTR_FLAGS_CLASS_CONDJUMP:
             info->insn_type = dis_condbranch;
             break;
           case S390_INSTR_FLAGS_CLASS_JUMPSR:
             info->insn_type = dis_jsr;
             break;
           default:
             info->insn_type = dis_nonbranch;
           }
         info->insn_info_valid = 1;

         /* The instruction is valid.  Print it and return its size.  */
         s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
         return opsize;
       }
   }

 /* For code sections it makes sense to skip unknown instructions
    according to their length bits.  */
 if (status == 0
     && option_use_insn_len_bits_p
     && info->section != NULL
     && (info->section->flags & SEC_CODE))
   bytes_to_dump = opsize;
 else
   /* By default unknown instructions are printed as .long's/.short'
      depending on how many bytes are available.  */
   bytes_to_dump = bufsize >= 4 ? 4 : bufsize;

 if (bytes_to_dump == 0)
   return 0;

 info->insn_type = dis_noninsn;
 info->insn_info_valid = 1;

 /* Fall back to hex print.  */
 switch (bytes_to_dump)
   {
   case 4:
     value = (unsigned int) buffer[0];
     value = (value << 8) + (unsigned int) buffer[1];
     value = (value << 8) + (unsigned int) buffer[2];
     value = (value << 8) + (unsigned int) buffer[3];
     info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
                                ".long");
     info->fprintf_styled_func (info->stream, dis_style_text,
                                "\t");
     info->fprintf_styled_func (info->stream, dis_style_immediate,
                                "0x%08x", value);
     return 4;
   case 2:
     value = (unsigned int) buffer[0];
     value = (value << 8) + (unsigned int) buffer[1];
     info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
                                ".short");
     info->fprintf_styled_func (info->stream, dis_style_text,
                                "\t");
     info->fprintf_styled_func (info->stream, dis_style_immediate,
                                "0x%04x", value);
     return 2;
   default:
     info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
                                ".byte");
     info->fprintf_styled_func (info->stream, dis_style_text,
                                "\t");
     info->fprintf_styled_func (info->stream, dis_style_immediate,
                                "0x%02x", (unsigned int) buffer[0]);
     for (i = 1; i < bytes_to_dump; i++)
       info->fprintf_styled_func (info->stream, dis_style_immediate,
                                  "0x%02x", (unsigned int) buffer[i]);
     return bytes_to_dump;
   }
 return 0;
}

const disasm_options_and_args_t *
disassembler_options_s390 (void)
{
 static disasm_options_and_args_t *opts_and_args;

 if (opts_and_args == NULL)
   {
     size_t i, num_options = ARRAY_SIZE (options);
     disasm_options_t *opts;

     opts_and_args = XNEW (disasm_options_and_args_t);
     opts_and_args->args = NULL;

     opts = &opts_and_args->options;
     opts->name = XNEWVEC (const char *, num_options + 1);
     opts->description = XNEWVEC (const char *, num_options + 1);
     opts->arg = NULL;
     for (i = 0; i < num_options; i++)
       {
         opts->name[i] = options[i].name;
         opts->description[i] = _(options[i].description);
       }
     /* The array we return must be NULL terminated.  */
     opts->name[i] = NULL;
     opts->description[i] = NULL;
   }

 return opts_and_args;
}

void
print_s390_disassembler_options (FILE *stream)
{
 unsigned int i, max_len = 0;
 fprintf (stream, _("\n\
The following S/390 specific disassembler options are supported for use\n\
with the -M switch (multiple options should be separated by commas):\n"));

 for (i = 0; i < ARRAY_SIZE (options); i++)
   {
     unsigned int len = strlen (options[i].name);
     if (max_len < len)
       max_len = len;
   }

 for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
   fprintf (stream, "  %s%*c %s\n",
            options[i].name,
            (int)(max_len - strlen (options[i].name)), ' ',
            _(options[i].description));
}

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