1/* s390-dis.c -- Disassemble S390 instructions
2   Copyright 2000, 2001, 2002 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., 59 Temple Place - Suite 330, Boston, MA
20   02111-1307, 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
28static int init_flag = 0;
29static int opc_index[256];
30static int current_arch_mask = 0;
31
32static void init_disasm PARAMS ((struct disassemble_info *));
33static unsigned int s390_extract_operand
34  PARAMS ((unsigned char *, const struct s390_operand *));
35
36/* Set up index table for first opcode byte.  */
37
38static void
39init_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
70static inline unsigned int
71s390_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
113int
114print_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}
262