Re: [Qemu-devel] [PATCH v4] m68k: implement movep instruction

["Pavel Dovgalyuk" <dovgaluk@ispras.ru>]

> From: Laurent Vivier [mailto:laurent@vivier.eu]
> Le 06/02/2018 à 13:44, Pavel Dovgalyuk a écrit :
> > This patch implements movep instruction. It moves data between a data register
> > and alternate bytes within the address space starting at the location
> > specified and incrementing by two.
> >
> > It was designed for the original 68000 and used in firmwares for
> > interfacing the 8-bit peripherals through the 16-bit data bus.
> 
> Did you test this change with some kind of firmware?

Yes, we implemented this instruction when tried to emulate Macintosh-128k on Qemu.

> > Without this patch opcode for this instruction is recognized as some bitop.
> >
> > Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
> > Signed-off-by: Mihail Abakumov <mikhail.abakumov@ispras.ru>
> >
> > --
> >
> > v4: - fixed offset calculation misprint
> >
> > v3: - simplified movep function code
> >     - joined movep masks
> >
> > v2: - disabled movep for Coldfire
> >     - fixed gen_store/load usage
> > ---
> >  target/m68k/cpu.c       |    2 ++
> >  target/m68k/cpu.h       |    1 +
> >  target/m68k/translate.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 49 insertions(+)
> 
> Tested-by: Laurent Vivier <laurent@vivier.eu>
> 
> I've checked we have the same result on a real 68040
> 
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Thanks!

By the way, we also handled reset interrupt, but it is not compatible with other m68k platforms:

@@ -66,8 +66,9 @@ static void m68k_cpu_reset(CPUState *s)
     cpu_m68k_set_fpcr(env, 0);
     env->fpsr = 0;
 
-    /* TODO: We should set PC from the interrupt vector.  */
-    env->pc = 0;
+    env->vbr = 0;
+    /* PC and SP (for m68k) will be initialized by the reset handler */
+    s->exception_index = EXCP_RESET;
 }

@@ -378,6 +380,8 @@ static void m68k_interrupt_all(CPUM68KState *env, int is_hw)
         cpu_m68k_set_sr(env, sr &= ~SR_M);
         sp = env->aregs[7] & ~1;
         do_stack_frame(env, &sp, 1, oldsr, 0, retaddr);
+    } else if (cs->exception_index == EXCP_RESET) {
+        sp = cpu_ldl_kernel(env, env->vbr + vector - 4);
     } else {
         do_stack_frame(env, &sp, 0, oldsr, 0, retaddr);
     }

Pavel Dovgalyuk