opcodes/s390-dis.c

   1 /* s390-dis.c -- Disassemble S390 instructions
   2    Copyright 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
   3    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
   4
   5    This file is part of GDB, GAS and the GNU binutils.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, USA.  */
  21
  22 #include <stdio.h>
  23 #include "ansidecl.h"
  24 #include "sysdep.h"
  25 #include "dis-asm.h"
  26 #include "opcode/s390.h"
  27
  28 static int init_flag = 0;
  29 static int opc_index[256];
  30 static int current_arch_mask = 0;
  31
  32 static void init_disasm PARAMS ((struct disassemble_info *));
  33 static unsigned int s390_extract_operand
  34   PARAMS ((unsigned char *, const struct s390_operand *));
  35
  36 /* Set up index table for first opcode byte.  */
  37
  38 static void
  39 init_disasm (info)
  40      struct disassemble_info *info;
  41 {
  42   const struct s390_opcode *opcode;
  43   const struct s390_opcode *opcode_end;
  44
  45   memset (opc_index, 0, sizeof (opc_index));
  46   opcode_end = s390_opcodes + s390_num_opcodes;
  47   for (opcode = s390_opcodes; opcode < opcode_end; opcode++)
  48     {
  49       opc_index[(int) opcode->opcode[0]] = opcode - s390_opcodes;
  50       while ((opcode < opcode_end) &&
  51              (opcode[1].opcode[0] == opcode->opcode[0]))
  52         opcode++;
  53     }
  54   switch (info->mach)
  55     {
  56     case bfd_mach_s390_31:
  57       current_arch_mask = 1 << S390_OPCODE_ESA;
  58       break;
  59     case bfd_mach_s390_64:
  60       current_arch_mask = 1 << S390_OPCODE_ZARCH;
  61       break;
  62     default:
  63       abort ();
  64     }
  65   init_flag = 1;
  66 }
  67
  68 /* Extracts an operand value from an instruction.  */
  69
  70 static inline unsigned int
  71 s390_extract_operand (insn, operand)
  72      unsigned char *insn;
  73      const struct s390_operand *operand;
  74 {
  75   unsigned int val;
  76   int bits;
  77
  78   /* Extract fragments of the operand byte for byte.  */
  79   insn += operand->shift / 8;
  80   bits = (operand->shift & 7) + operand->bits;
  81   val = 0;
  82   do
  83     {
  84       val <<= 8;
  85       val |= (unsigned int) *insn++;
  86       bits -= 8;
  87     }
  88   while (bits > 0);
  89   val >>= -bits;
  90   val &= ((1U << (operand->bits - 1)) << 1) - 1;
  91
  92   /* Check for special long displacement case.  */
  93   if (operand->bits == 20 && operand->shift == 20)
  94     val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
  95
  96   /* Sign extend value if the operand is signed or pc relative.  */
  97   if ((operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
  98       && (val & (1U << (operand->bits - 1))))
  99     val |= (-1U << (operand->bits - 1)) << 1;
 100
 101   /* Double value if the operand is pc relative.  */
 102   if (operand->flags & S390_OPERAND_PCREL)
 103     val <<= 1;
 104
 105   /* Length x in an instructions has real length x+1.  */
 106   if (operand->flags & S390_OPERAND_LENGTH)
 107     val++;
 108   return val;
 109 }
 110
 111 /* Print a S390 instruction.  */
 112
 113 int
 114 print_insn_s390 (memaddr, info)
 115      bfd_vma memaddr;
 116      struct disassemble_info *info;
 117 {
 118   bfd_byte buffer[6];
 119   const struct s390_opcode *opcode;
 120   const struct s390_opcode *opcode_end;
 121   unsigned int value;
 122   int status, opsize, bufsize;
 123   char separator;
 124
 125   if (init_flag == 0)
 126     init_disasm (info);
 127
 128   /* The output looks better if we put 6 bytes on a line.  */
 129   info->bytes_per_line = 6;
 130
 131   /* Every S390 instruction is max 6 bytes long.  */
 132   memset (buffer, 0, 6);
 133   status = (*info->read_memory_func) (memaddr, buffer, 6, info);
 134   if (status != 0)
 135     {
 136       for (bufsize = 0; bufsize < 6; bufsize++)
 137         if ((*info->read_memory_func) (memaddr, buffer, bufsize + 1, info) != 0)
 138           break;
 139       if (bufsize <= 0)
 140         {
 141           (*info->memory_error_func) (status, memaddr, info);
 142           return -1;
 143         }
 144       /* Opsize calculation looks strange but it works
 145          00xxxxxx -> 2 bytes, 01xxxxxx/10xxxxxx -> 4 bytes,
 146          11xxxxxx -> 6 bytes.  */
 147       opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
 148       status = opsize > bufsize;
 149     }
 150   else
 151     {
 152       bufsize = 6;
 153       opsize = ((((buffer[0] >> 6) + 1) >> 1) + 1) << 1;
 154     }
 155
 156   if (status == 0)
 157     {
 158       /* Find the first match in the opcode table.  */
 159       opcode_end = s390_opcodes + s390_num_opcodes;
 160       for (opcode = s390_opcodes + opc_index[(int) buffer[0]];
 161            (opcode < opcode_end) && (buffer[0] == opcode->opcode[0]);
 162            opcode++)
 163         {
 164           const struct s390_operand *operand;
 165           const unsigned char *opindex;
 166
 167           /* Check architecture.  */
 168           if (!(opcode->modes & current_arch_mask))
 169             continue;
 170           /* Check signature of the opcode.  */
 171           if ((buffer[1] & opcode->mask[1]) != opcode->opcode[1]
 172               || (buffer[2] & opcode->mask[2]) != opcode->opcode[2]
 173               || (buffer[3] & opcode->mask[3]) != opcode->opcode[3]
 174               || (buffer[4] & opcode->mask[4]) != opcode->opcode[4]
 175               || (buffer[5] & opcode->mask[5]) != opcode->opcode[5])
 176             continue;
 177
 178           /* The instruction is valid.  */
 179           if (opcode->operands[0] != 0)
 180             (*info->fprintf_func) (info->stream, "%s\t", opcode->name);
 181           else
 182             (*info->fprintf_func) (info->stream, "%s", opcode->name);
 183
 184           /* Extract the operands.  */
 185           separator = 0;
 186           for (opindex = opcode->operands; *opindex != 0; opindex++)
 187             {
 188               unsigned int value;
 189
 190               operand = s390_operands + *opindex;
 191               value = s390_extract_operand (buffer, operand);
 192
 193               if ((operand->flags & S390_OPERAND_INDEX) && value == 0)
 194                 continue;
 195               if ((operand->flags & S390_OPERAND_BASE) &&
 196                   value == 0 && separator == '(')
 197                 {
 198                   separator = ',';
 199                   continue;
 200                 }
 201
 202               if (separator)
 203                 (*info->fprintf_func) (info->stream, "%c", separator);
 204
 205               if (operand->flags & S390_OPERAND_GPR)
 206                 (*info->fprintf_func) (info->stream, "%%r%i", value);
 207               else if (operand->flags & S390_OPERAND_FPR)
 208                 (*info->fprintf_func) (info->stream, "%%f%i", value);
 209               else if (operand->flags & S390_OPERAND_AR)
 210                 (*info->fprintf_func) (info->stream, "%%a%i", value);
 211               else if (operand->flags & S390_OPERAND_CR)
 212                 (*info->fprintf_func) (info->stream, "%%c%i", value);
 213               else if (operand->flags & S390_OPERAND_PCREL)
 214                 (*info->print_address_func) (memaddr + (int) value, info);
 215               else if (operand->flags & S390_OPERAND_SIGNED)
 216                 (*info->fprintf_func) (info->stream, "%i", (int) value);
 217               else
 218                 (*info->fprintf_func) (info->stream, "%i", value);
 219
 220               if (operand->flags & S390_OPERAND_DISP)
 221                 {
 222                   separator = '(';
 223                 }
 224               else if (operand->flags & S390_OPERAND_BASE)
 225                 {
 226                   (*info->fprintf_func) (info->stream, ")");
 227                   separator = ',';
 228                 }
 229               else
 230                 separator = ',';
 231             }
 232
 233           /* Found instruction, printed it, return its size.  */
 234           return opsize;
 235         }
 236       /* No matching instruction found, fall through to hex print.  */
 237     }
 238
 239   if (bufsize >= 4)
 240     {
 241       value = (unsigned int) buffer[0];
 242       value = (value << 8) + (unsigned int) buffer[1];
 243       value = (value << 8) + (unsigned int) buffer[2];
 244       value = (value << 8) + (unsigned int) buffer[3];
 245       (*info->fprintf_func) (info->stream, ".long\t0x%08x", value);
 246       return 4;
 247     }
 248   else if (bufsize >= 2)
 249     {
 250       value = (unsigned int) buffer[0];
 251       value = (value << 8) + (unsigned int) buffer[1];
 252       (*info->fprintf_func) (info->stream, ".short\t0x%04x", value);
 253       return 2;
 254     }
 255   else
 256     {
 257       value = (unsigned int) buffer[0];
 258       (*info->fprintf_func) (info->stream, ".byte\t0x%02x", value);
 259       return 1;
 260     }
 261 }