File I/O in H8300 Simulator

["D.Venkatasubramanian, Noida" <dvenkat at noida dot hcltech dot com>]

Hi All,

I was intending to add File I/O support to the H8300 simulator
code. And the system calls that I was intending to modify were
creat, open, read, write, seek and close.

Since the support for read was present in the newlib, I started 
out with adding reading from stdin support in the sim. I am 
submitting a patch which does the same.

I was thinking of adopting a similar strategy for handling the
other system calls, (branch to some location like 0xc5, 0xc6 etc.)
for different system calls and handle these through simulator. For
these system calls, I need to do some modifications on newlib too.
I may need to change the current implementation of read and write
again to handle host files.

Please let me know, if this is OK.

Thanks and Regards,

Venky


*** include/opcode/h8300.h.original     Thu Oct 24 15:56:06 2002
--- include/opcode/h8300.h.modified     Mon Oct 28 12:40:18 2002
*************** struct h8_opcode
*** 305,310 ****
--- 305,317 ----
  #define O_STM 86
  #define O_STMAC 87
  #define O_LAST 88
+ /* Change made for System Call processing */
+ #define O_SYS_CREAT 100
+ #define O_SYS_OPEN 101
+ #define O_SYS_READ 102
+ #define O_SYS_WRITE 103
+ #define O_SYS_SEEK 104
+ /* End of Changes */
  #define SB 0
  #define SW 1
  #define SL 2
*** sim/h8300/compile.c.original        Mon Oct 28 13:03:12 2002
--- sim/h8300/compile.c.modified        Mon Oct 28 13:03:20 2002
*************** decode (addr, data, dst)
*** 448,464 ****
                  dst->opcode = q->how;
                  dst->cycles = q->time;

!                 /* And a jsr to 0xc4 is turned into a magic trap.  */

                  if (dst->opcode == O (O_JSR, SB))
                    {
                      if (dst->src.literal == 0xc4)
                        {
!                         dst->opcode = O (O_SYSCALL, SB);
                        }
                    }
!
!                 dst->next_pc = addr + len / 2;
                  return;
                }
              else
--- 448,469 ----
                  dst->opcode = q->how;
                  dst->cycles = q->time;

!                 /* And a jsr to 0xc4 or 0xc8 is turned into a magic trap.
*/
!                   /* System Call Processing */

                  if (dst->opcode == O (O_JSR, SB))
                    {
                      if (dst->src.literal == 0xc4)
                        {
!                         dst->opcode = O (O_SYS_WRITE, SB);
!                       }
!                     else if (dst->src.literal == 0xc8)
!                       {
!                         dst->opcode = O (O_SYS_READ, SB);
                        }
                    }
!
!                   dst->next_pc = addr + len / 2;
                  return;
                }
              else
*************** sim_resume (sd, step, siggnal)
*** 1392,1405 ****
            goto condtrue;
          goto next;

!         case O (O_SYSCALL, SB):
            {
            char c = cpu.regs[2];
            sim_callback->write_stdout (sim_callback, &c, 1);
          }
            goto next;

!         ONOT (O_NOT, rd = ~rd; v = 0;);
          OSHIFTS (O_SHLL,
                   c = rd & hm; v = 0; rd <<= 1,
                   c = rd & (hm >> 1); v = 0; rd <<= 2);
--- 1397,1418 ----
            goto condtrue;
          goto next;

! /* System Call Processing */
!       case O (O_SYS_WRITE, SB):
            {
            char c = cpu.regs[2];
            sim_callback->write_stdout (sim_callback, &c, 1);
          }
            goto next;
+         case O (O_SYS_READ, SB):
+           {
+           char d ;
+           sim_callback->read_stdin (sim_callback, &d, 1);
+             SET_MEMORY_B (cpu.regs[2], d);
+         }
+         goto next;

!           ONOT (O_NOT, rd = ~rd; v = 0;);
          OSHIFTS (O_SHLL,
                   c = rd & hm; v = 0; rd <<= 1,
                   c = rd & (hm >> 1); v = 0; rd <<= 2);




Change Log entries

Mon Oct 28 14:12:42 IST 2002 D.Venkatasubramanian
<dvenkat@noida.hcltech.com>

        * compile.c (decode): Added code to recognize a read system
        call and modified to recognize write system call.

        * compile.c (sim_resume): Added code for handling read system
        call and modified code for write.


Mon Oct 28 12:41:37 IST 2002 D.Venkatasubramanian
<dvenkat@noida.hcltech.com>

        * h8300.h : Added some # defines for system call processing.
        These system calls are being introduced as pseudo opcodes
        for system call handling in the simulator. This is similar
        to the O_SYSCALL entry already present.