Simplify bit bookkeeping

In preparation of adding several additional finger bit registers,
remove the redundant bit-counting variables and introduce fast
bit-traversal functions instead.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

5 files changed, 43 insertions, 21 deletions

diff --git a/src/common.h b/src/common.h
index 27082b7..1b4d007 100644
--- a/src/common.h
+++ b/src/common.h
@@ -61,4 +61,19 @@
 #define SETBIT(m, x) (m |= BITMASK(x))
 #define CLEARBIT(m, x) (m &= ~BITMASK(x))
 
+/* Count number of bits (Sean Eron Andersson's Bit Hacks) */
+static inline int bitcount(unsigned v)
+{
+	v -= ((v>>1) & 0x55555555);
+	v = (v&0x33333333) + ((v>>2) & 0x33333333);
+	return (((v + (v>>4)) & 0xF0F0F0F) * 0x1010101) >> 24;
+}
+
+/* Return index of first bit [0-31], -1 on zero */
+#define firstbit(v) (__builtin_ffs(v) - 1)
+
+/* boost-style foreach bit */
+#define foreach_bit(i, m)						\
+	for (i = firstbit(m); i >= 0; i = firstbit((m) & (~0U << i + 1)))
+
 #endif
diff --git a/src/gestures.c b/src/gestures.c
index 7346043..f44e6ab 100644
--- a/src/gestures.c
+++ b/src/gestures.c
@@ -58,7 +58,6 @@ static void extract_pointers(struct Gestures *gs, struct MTouch* mt)
 
 	if (mt->state.nfinger < 2) {
 		mt->mem.pointing = mt->state.nfinger;
-		mt->mem.npoint = mt->state.nfinger;
 		mt->mem.ybar = mt->caps.abs_position_y.maximum;
 		return;
 	}
@@ -69,7 +68,6 @@ static void extract_pointers(struct Gestures *gs, struct MTouch* mt)
 				continue;
 			if (f[i].hw.position_y <= mt->mem.ybar) {
 				mt->mem.pointing = BITONES(mt->state.nfinger);
-				mt->mem.npoint = mt->state.nfinger;
 				return;
 			}
 		}
@@ -77,15 +75,13 @@ static void extract_pointers(struct Gestures *gs, struct MTouch* mt)
 	}
 
 	mt->mem.pointing = 0;
-	mt->mem.npoint = 0;
 	mt->mem.ybar = mt->caps.yclick;
 	for (i = 0; i < mt->state.nfinger; i++) {
 		if (f[i].hw.position_y > mt->caps.yclick)
 			continue;
-		if (!mt->mem.npoint || f[i].hw.position_y > mt->mem.ybar)
+		if (!mt->mem.pointing || f[i].hw.position_y > mt->mem.ybar)
 			mt->mem.ybar = f[i].hw.position_y;
 		SETBIT(mt->mem.pointing, i);
-		mt->mem.npoint++;
 	}
 
 }
@@ -97,7 +93,6 @@ static void extract_movement(struct Gestures *gs, struct MTouch* mt)
 	int dx, dy, xcut, ycut, xmax = 0, ymax = 0;
 
 	mt->mem.moving = 0;
-	mt->mem.nmove = 0;
 
 	if (mt->state.nfinger == 0)
 		return;
@@ -128,22 +123,21 @@ static void extract_movement(struct Gestures *gs, struct MTouch* mt)
 			if (!GETBIT(mt->mem.pointing, i))
 				continue;
 			if (abs(mt->mem.dx[i]) > xcut ||
-			    abs(mt->mem.dy[i]) > ycut) {
+			    abs(mt->mem.dy[i]) > ycut)
 				SETBIT(mt->mem.moving, i);
-				mt->mem.nmove++;
-			}
 		}
 
 		/* accumulate all movement during delay */
-		if (mt->mem.nmove && mt->state.evtime >= mt->mem.move_time) {
+		if (mt->mem.moving && mt->state.evtime >= mt->mem.move_time) {
+			int nmove = bitcount(mt->mem.moving);
 			for (i = 0; i < mt->state.nfinger; i++) {
 				if (GETBIT(mt->mem.moving, i)) {
 					gs->dx += mt->mem.dx[i];
 					gs->dy += mt->mem.dy[i];
 				}
 			}
-			gs->dx /= mt->mem.nmove;
-			gs->dy /= mt->mem.nmove;
+			gs->dx /= nmove;
+			gs->dy /= nmove;
 			memset(mt->mem.dx, 0, sizeof(mt->mem.dx));
 			memset(mt->mem.dy, 0, sizeof(mt->mem.dy));
 		}
@@ -153,10 +147,11 @@ static void extract_movement(struct Gestures *gs, struct MTouch* mt)
 static void extract_buttons(struct Gestures *gs, struct MTouch* mt)
 {
 	unsigned btdata = mt->state.button & BITONES(DIM_BUTTON);
+	int npoint = bitcount(mt->mem.pointing);
 	if (mt->state.button == BITMASK(MT_BUTTON_LEFT)) {
-		if (mt->mem.npoint == 2)
+		if (npoint == 2)
 			btdata = BITMASK(MT_BUTTON_RIGHT);
-		if (mt->mem.npoint == 3)
+		if (npoint == 3)
 			btdata = BITMASK(MT_BUTTON_MIDDLE);
 	}
 	if (mt->state.button != mt->prev_state.button) {
@@ -170,18 +165,19 @@ static void extract_buttons(struct Gestures *gs, struct MTouch* mt)
 
 static void extract_type(struct Gestures *gs, struct MTouch* mt)
 {
+	int npoint = bitcount(mt->mem.pointing);
 	if (gs->btmask)
 		SETBIT(gs->type, GS_BUTTON);
 	if (gs->dx || gs->dy) {
-		if (mt->mem.npoint == 1)
+		if (npoint == 1)
 			SETBIT(gs->type, GS_MOVE);
-		if (mt->mem.npoint == 2) {
+		if (npoint == 2) {
 			if (gs->dx)
 				SETBIT(gs->type, GS_HSCROLL);
 			if (gs->dy)
 				SETBIT(gs->type, GS_VSCROLL);
 		}
-		if (mt->mem.npoint == 3) {
+		if (npoint == 3) {
 			if (gs->dx)
 				SETBIT(gs->type, GS_HSWIPE);
 			if (gs->dy)
diff --git a/src/memory.c b/src/memory.c
index 15b483c..0e2edba 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -32,8 +32,6 @@ void output_memory(const struct Memory *m)
 	xf86Msg(X_INFO, "btdata: %04x\n", m->btdata);
 	xf86Msg(X_INFO, "pointing: %04x\n", m->pointing);
 	xf86Msg(X_INFO, "moving: %04x\n", m->moving);
-	xf86Msg(X_INFO, "npoint: %d\n", m->npoint);
 	xf86Msg(X_INFO, "ybar: %d\n", m->ybar);
 	xf86Msg(X_INFO, "move_time: %lld\n", m->move_time);
-	xf86Msg(X_INFO, "nmove: %d\n", m->nmove);
 }
diff --git a/src/memory.h b/src/memory.h
index 81cdae0..23d2ce6 100644
--- a/src/memory.h
+++ b/src/memory.h
@@ -26,9 +26,9 @@
 
 struct Memory {
 	unsigned btdata, pointing, moving;
-	int npoint, ybar;
+	int ybar;
 	mstime_t move_time;
-	int dx[DIM_FINGER], dy[DIM_FINGER], nmove;
+	int dx[DIM_FINGER], dy[DIM_FINGER];
 
 
 
diff --git a/src/test.c b/src/test.c
index e9b8ce3..fc16201 100644
--- a/src/test.c
+++ b/src/test.c
@@ -19,10 +19,23 @@
  *
  **************************************************************************/
 
+#include "common.h"
 #include <stdio.h>
 #include <time.h>
 
+static void print_bitfield(unsigned m)
+{
+	int i;
+
+	printf("%d\n", m);
+	foreach_bit(i, m)
+		printf("%d %d\n", i, 1 << i);
+}
+
 int main(int argc, char *argv[])
 {
+	print_bitfield(5);
+	print_bitfield(126);
+	print_bitfield(0);
 	return 0;
 }