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Turbocharge mouse movement

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.. by storing directly into the vars used by the mac plus ROM,
rather than working through the IRQ & I/O subsystems.
This commit is contained in:
Jeff Epler 2025-08-01 15:41:43 -05:00
parent d7d30c5608
commit d86ebf1bb8
1 changed files with 14 additions and 77 deletions
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91
src/main.c
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@ -615,94 +615,32 @@ void umac_opt_disassemble(int enable)
disassemble = enable; disassemble = enable;
} }
#define MOUSE_MAX_PENDING_PIX 30
static int pending_mouse_deltax = 0;
static int pending_mouse_deltay = 0;
/* Provide mouse input (movement, button) data. /* Provide mouse input (movement, button) data.
* *
* X is positive going right; Y is positive going upwards. * X is positive going right; Y is positive going upwards.
*/ */
void umac_mouse(int deltax, int deltay, int button) void umac_mouse(int deltax, int deltay, int button)
{ {
pending_mouse_deltax += deltax; #define MTemp_h 0x82a
pending_mouse_deltay += deltay; #define MTemp_v 0x828
#define CrsrNew 0x8ce
#define CrsrCouple 0x8cf
/* Clamp if the UI has flooded with lots and lots of steps! if(deltax) {
*/ int16_t temp_h = RAM_RD16(MTemp_h) + deltax;
if (pending_mouse_deltax > MOUSE_MAX_PENDING_PIX) RAM_WR16(MTemp_h, temp_h);
pending_mouse_deltax = MOUSE_MAX_PENDING_PIX;
if (pending_mouse_deltax < -MOUSE_MAX_PENDING_PIX)
pending_mouse_deltax = -MOUSE_MAX_PENDING_PIX;
if (pending_mouse_deltay > MOUSE_MAX_PENDING_PIX)
pending_mouse_deltay = MOUSE_MAX_PENDING_PIX;
if (pending_mouse_deltay < -MOUSE_MAX_PENDING_PIX)
pending_mouse_deltay = -MOUSE_MAX_PENDING_PIX;
/* FIXME: The movement might take a little time, but this
* posts the button status immediately. Probably OK, but the
* mismatch might be perceptible.
*/
via_mouse_pressed = button;
}
static void mouse_tick(void)
{
/* Periodically, check if the mouse X/Y deltas are non-zero.
* If a movement is required, encode one step in X and/or Y
* and deduct from the pending delta.
*
* The step ultimately posts an SCC IRQ, so we _don't_ try to
* make any more steps while an IRQ is currently pending.
* (Currently, that means a previous step's DCD IRQ event
* hasn't yet been consumed by the OS handler. In future, if
* SCC is extended with other IRQ types, then just checking
* the IRQ status is technically too crude, but should still
* be fine given the timeframes.)
*/
if (pending_mouse_deltax == 0 && pending_mouse_deltay == 0)
return;
if (scc_irq_state == 1)
return;
static int old_dcd_a = 0;
static int old_dcd_b = 0;
/* Mouse X/Y quadrature signals are wired to:
* VIA Port B[4] & SCC DCD_A for X
* VIA Port B[5] & SCC DCD_B for Y
*
* As VIA mouse signals aren't sampled until IRQ, can do this
* in one step, toggling existing DCD states and setting VIA
* either equal or opposite to DCD:
*/
int dcd_a = old_dcd_a;
int dcd_b = old_dcd_b;
int deltax = pending_mouse_deltax;
int deltay = pending_mouse_deltay;
uint8_t qb = via_quadbits;
if (deltax) {
dcd_a = !dcd_a;
qb = (qb & ~0x10) | ((deltax < 0) == dcd_a ? 0x10 : 0);
pending_mouse_deltax += (deltax > 0) ? -1 : 1;
MDBG(" px %d, oldpx %d", pending_mouse_deltax, deltax);
} }
if (deltay) { if (deltay) {
dcd_b = !dcd_b; int16_t temp_v = RAM_RD16(MTemp_v) - deltay;
qb = (qb & ~0x20) | ((deltay < 0) == dcd_b ? 0x20 : 0); RAM_WR16(MTemp_v, temp_v);
pending_mouse_deltay += (deltay > 0) ? -1 : 1;
MDBG(" py %d, oldpy %d", pending_mouse_deltay, deltay);
} }
MDBG("\n");
via_quadbits = qb; if(deltax || deltay) {
old_dcd_a = dcd_a; RAM_WR8(CrsrNew, RAM_RD8(CrsrCouple));
old_dcd_b = dcd_b; }
scc_set_dcd(dcd_a, dcd_b);
via_mouse_pressed = button;
} }
void umac_reset(void) void umac_reset(void)
@ -734,7 +672,6 @@ int umac_loop(void)
// Device polling // Device polling
via_tick(global_time_us); via_tick(global_time_us);
mouse_tick();
disc_tick(); disc_tick();
kbd_check_work(); kbd_check_work();