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Minor speed improvement to the e132xs core - don't pass opcode parameter when calling instruction handlers [Christophe Jaillet]

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> -----Original Message-----
> From: Christophe Jaillet [mailto:christophe.jaillet@wanadoo.fr]
> Sent: Saturday, October 17, 2009 9:00 AM
> To: submit@mamedev.org
> Subject: Speed up emu\cpu\e132xs
>
> Hi,
>
> this patch speeds up the emulation of the CPU e132xs.
>
> For the emulation of this CPU, two structures are used :
>     - '_hyperstone_state' which keep track of the state of the
> processor
>     - 'regs_decode' which is used when decoding the opcode being
> executed
>
> Both of these structures have a field 'op' but only the one of
> 'regs_decode'
> is actually used.
>
> The emulation of the CPU is done this way :
>     - read the opcode
>     - call the corresponding function which emulate this opcode. Two
> parameters are passed :
>         o a pointer to hyperstone_state
>         o the opcode itself
>     - the opcode is then stored in the relevant field of a local stack
> stored 'regs_decode' structure.
>
> The field 'op' of  '_hyperstone_state' is never used.
>
>
> So the proposed patch does the following :
>     - use the 'op' field of '_hyperstone_state' instead of the one of
> 'regs_decode'
>     - initialise this 'op' field before calling the function which
> emulate
> this opcode
>     - remove the need of the second parameter ('opcode') of these
> functions
>     - remove the now useless 'op' field of the structure 'regs_decode'
>
> Doing so removes the need of pushing a parameter on the stack for each
> opcode simulated and give a average speed up of 1 % or 2 % of the
> emulation.
>
> Hope this help.
> Best regards,
>
> CJ
This commit is contained in:
Phil Bennett 2009-10-21 11:27:56 +00:00
parent 0279e10c26
commit 8b28c00872
2 changed files with 260 additions and 263 deletions
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8
src/emu/cpu/e132xs/e132xs.c
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@ -349,7 +349,6 @@ struct regs_decode
UINT8 same_src_dst;
UINT8 same_src_dstf;
UINT8 same_srcf_dst;
UINT16 op;
};
static void check_interrupts(hyperstone_state *cpustate);
@ -360,7 +359,6 @@ static void check_interrupts(hyperstone_state *cpustate);
#define DREGF (decode)->next_dst_value
#define EXTRA_U (decode)->extra.u
#define EXTRA_S (decode)->extra.s
#define OP (decode)->op
#define SET_SREG( _data_ ) ((decode)->src_is_local ? set_local_register(cpustate, (decode)->src, _data_) : set_global_register(cpustate, (decode)->src, _data_))
#define SET_SREGF( _data_ ) ((decode)->src_is_local ? set_local_register(cpustate, (decode)->src + 1, _data_) : set_global_register(cpustate, (decode)->src + 1, _data_))
@ -500,6 +498,7 @@ static void hyperstone_set_trap_entry(hyperstone_state *cpustate, int which)
}
}
#define OP cpustate->op
#define PPC cpustate->ppc //previous pc
#define PC cpustate->global_regs[0] //Program Counter
#define SR cpustate->global_regs[1] //Status Register
@ -4671,18 +4670,17 @@ static CPU_EXECUTE( hyperstone )
do
{
UINT32 oldh = SR & 0x00000020;
UINT16 opcode;
PPC = PC; /* copy PC to previous PC */
debugger_instruction_hook(device, PC);
opcode = READ_OP(cpustate, PC);
OP = READ_OP(cpustate, PC);
PC += 2;
cpustate->instruction_length = 1;
/* execute opcode */
(*hyperstone_op[(opcode & 0xff00) >> 8])(cpustate, opcode);
(*hyperstone_op[(OP & 0xff00) >> 8])(cpustate);
/* clear the H state if it was previously set */
SR ^= oldh;

515
src/emu/cpu/e132xs/e132xsop.c
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