static READ_HANDLER( tp84_sh_timer_r )
{
/* main xtal 14.318MHz, divided by 4 to get the CPU clock, further */
/* divided by 2048 to get this timer */
/* (divide by (2048/2), and not 1024, because the CPU cycle counter is */
/* incremented every other state change of the clock) */
return (cpu_gettotalcycles() / (2048/2)) & 0x0f;
}
int circusc_sh_timer_r(int offset)
{
int clock;
#define CIRCUSCHALIE_TIMER_RATE (14318180/6144)
clock = (cpu_gettotalcycles()*4) / CIRCUSCHALIE_TIMER_RATE;
return clock & 0xF;
}
int mikie_sh_timer_r(int offset)
{
int clock;
#define TIMER_RATE 512
clock = cpu_gettotalcycles() / TIMER_RATE;
return clock;
}
static READ_HANDLER( junofrst_portA_r )
{
int timer;
/* main xtal 14.318MHz, divided by 8 to get the CPU clock, further */
/* divided by 1024 to get this timer */
/* (divide by (1024/2), and not 1024, because the CPU cycle counter is */
/* incremented every other state change of the clock) */
timer = (cpu_gettotalcycles() / (1024/2)) & 0x0f;
/* low three bits come from the 8039 */
return (timer << 4) | i8039_status;
}
static READ_HANDLER( tempest_IN0_r )
{
int res;
res = readinputport(0);
if (avgdvg_done())
res|=0x40;
/* Emulate the 3Khz source on bit 7 (divide 1.5Mhz by 512) */
if (cpu_gettotalcycles() & 0x100)
res |=0x80;
return res;
}
int gyruss_portA_r(int offset)
{
/* need to protect from totalcycles overflow */
static int last_totalcycles = 0;
/* number of Z80 clock cycles to count */
static int clock;
int current_totalcycles;
current_totalcycles = cpu_gettotalcycles();
clock = (clock + (current_totalcycles-last_totalcycles)) % 10240;
last_totalcycles = current_totalcycles;
return gyruss_timer[clock/1024];
}
int frogger_portB_r(int offset)
{
/* need to protect from totalcycles overflow */
static int last_totalcycles = 0;
/* number of Z80 clock cycles to count */
static int clock;
int current_totalcycles;
current_totalcycles = cpu_gettotalcycles();
clock = (clock + (current_totalcycles-last_totalcycles)) % 5120;
last_totalcycles = current_totalcycles;
return frogger_timer[clock/512];
}
static READ_HANDLER( timeplt_portB_r )
{
/* need to protect from totalcycles overflow */
static int last_totalcycles = 0;
/* number of Z80 clock cycles to count */
static int clock;
int current_totalcycles;
current_totalcycles = cpu_gettotalcycles();
clock = (clock + (current_totalcycles-last_totalcycles)) % 5120;
last_totalcycles = current_totalcycles;
return timeplt_timer[clock/512];
}
int megazone_portA_r(int offset)
{
int clock,timer;
/* main xtal 14.318MHz, divided by 8 to get the AY-3-8910 clock, further */
/* divided by 1024 to get this timer */
/* The base clock for the CPU and 8910 is NOT the same, so we have to */
/* compensate. */
/* (divide by (1024/2), and not 1024, because the CPU cycle counter is */
/* incremented every other state change of the clock) */
clock = cpu_gettotalcycles() * 7159/12288; /* = (14318/8)/(18432/6) */
timer = (clock / (1024/2)) & 0x0f;
/* low three bits come from the 8039 */
return (timer << 4) | i8039_status;
}
int cop01_sound_command_r(int offset)
{
int res;
static int pulse;
#define TIMER_RATE 12000 /* total guess */
res = (soundlatch_r(offset) & 0x7f) << 1;
/* bit 0 seems to be a timer */
if ((cpu_gettotalcycles() / TIMER_RATE) & 1)
{
if (pulse == 0) res |= 1;
pulse = 1;
}
else pulse = 0;
return res;
}
static READ_HANDLER( pandoras_portB_r )
{
/* ??? */
return (cpu_gettotalcycles() / 1024) & 0x0f;
}
