Add initial mouse support

Makefile

@@ -9,6 +9,8 @@ TAL_SRC   ?= $(BASE_UXN)/projects/examples/devices/screen.tal
 UXN_ROM    ?= $(BUILD_DIR)/rom.rom
 UXN_ASM    ?= $(BUILD_DIR)/uxnasm
 KBD_PATH   ?= /dev/input/event1
+MOUSE_PATH ?= /dev/input/mice
+C_DEFINES  := -DKBD_PATH=\"$(KBD_PATH)\" -DMOUSE_PATH=\"$(MOUSE_PATH)\"
 
 CC        ?= cc
 CFLAGS    := -Wall -Wextra -pedantic
@@ -30,7 +32,7 @@ endif
 main: $(BIN)
 
 $(BIN): $(SRC_MAIN) $(BUILD_DIR) $(UXN_HEAD)
-	$(CC) $(CFLAGS) -o $(BIN) $(SRC_MAIN) -DKBD_PATH=\"$(KBD_PATH)\"
+	$(CC) $(CFLAGS) -o $(BIN) $(SRC_MAIN) $(C_DEFINES)
 
 $(BUILD_DIR):
 	mkdir -p $(BUILD_DIR)

src/main.c

@@ -12,6 +12,8 @@
 #include "ppu.c"
 #include "uxn-fast.c"
 
+#define CLAMP(X, MIN, MAX) ((X) <= (MIN) ? (MIN) : (X) > (MAX) ? (MAX): (X))
+
 static Uxn u;
 static Device *devscreen;
 static Device *devctrl;
@@ -33,42 +35,93 @@ time_elapsed(Time since){
     return (now.tv_sec - since.tv_sec) * 1e9 + (now.tv_nsec - since.tv_nsec);
 }
 
+typedef struct Mouse {
+    s32 x;
+    s32 y;
+    bool left;
+    bool mid;
+    bool right;
+    bool update;
+} Mouse;
+
 typedef struct Input {
-    int kb_fd;
+    int kbd_fd;
+    int mouse_fd;
     char map[KEY_MAX / 8 + 1];
     u8 controller;
+    Mouse mouse;
 } Input;
 
-static Input input;
+// NOTE: For event codes and input documentation:
+// - https://www.kernel.org/doc/Documentation/input/event-codes.txt
+// - /usr/include/linux/input.h
+static Input in;
 
 void
 init_input(void) {
-    memset(&input, 0, sizeof(input));
+    memset(&in, 0, sizeof(in));
-    input.kb_fd = -1;
+    in.kbd_fd = -1;
+    in.mouse_fd = -1;
 
-    const char *dev = KBD_PATH;
+    in.kbd_fd = open(KBD_PATH, O_RDONLY | O_NONBLOCK);
-    input.kb_fd = open(dev, O_RDONLY);
+    if (in.kbd_fd == -1) {
-    if (input.kb_fd == -1) {
         // NOTE: Some applications may not require a keyboard so this is
         //       optional, but we are still displaying an error.
-        fprintf(stderr, "error: no couldn't open keyboard %s: %s.\n", dev, strerror(errno));
+        fprintf(stderr, "error: no couldn't open keyboard %s: %s.\n", KBD_PATH, strerror(errno));
+    }
+
+    in.mouse_fd = open(MOUSE_PATH, O_RDONLY | O_NONBLOCK);
+    if (in.mouse_fd == -1) {
+        // NOTE: Some applications may not require a mouse so this is
+        //       optional, but we are still displaying an error.
+        fprintf(stderr, "error: no couldn't open mouse %s: %s.\n", MOUSE_PATH, strerror(errno));
     }
 }
 
 void
 poll_keyboard(void) {
-    if (input.kb_fd == -1) {
+    if (in.kbd_fd == -1) {
         return;
     }
 
+    // TODO: use read() instead to avoid updating the keyboard if no events have
+    //       occurred. Similar to the mouse implementation.
     char map[KEY_MAX / 8 + 1];
     memset(map, 0, sizeof(map));
-    ioctl(input.kb_fd, EVIOCGKEY(sizeof(map)), map);
+    ioctl(in.kbd_fd, EVIOCGKEY(sizeof(map)), map);
     for (size_t i = 0; i < sizeof(map); i++) {
-        input.map[i] |= map[i];
+        in.map[i] |= map[i];
     }
 }
 
+void
+poll_mouse(void) {
+    if (in.mouse_fd == -1) {
+        return;
+    }
+
+    struct input_event mouse_event;
+    if (read(in.mouse_fd, &mouse_event, sizeof(mouse_event)) != -1) {
+        if (mouse_event.type == EV_REL) {
+            if (mouse_event.code == REL_X) {
+                in.mouse.x = CLAMP(
+                    in.mouse.x + (s32)mouse_event.value, 0, (s32)screen_width);
+            } else  if (mouse_event.code == REL_Y) {
+                in.mouse.y = CLAMP(
+                    in.mouse.y + (s32)mouse_event.value, 0, (s32)screen_height);
+            }
+        }
+        in.mouse.update = true;
+        // TODO: Handle mouse keys
+    }
+}
+
+void
+poll_input(void) {
+    poll_keyboard();
+    poll_mouse();
+}
+
 void
 handle_keyboard(void) {
     // Find mod keys.
@@ -76,9 +129,9 @@ handle_keyboard(void) {
     // bool ctrl_mod = false;
     // bool alt_mod = false;
     // bool meta_mod = false;
-    for (size_t i = 0; i < sizeof(input.map); i++) {
+    for (size_t i = 0; i < sizeof(in.map); i++) {
         for (size_t j = 0; j < 8; j++) {
-            char key = input.map[i] & (1 << j);
+            char key = in.map[i] & (1 << j);
             if (key) {
                 char key_code = i * 8 + j;
                 switch (key_code) {
@@ -98,9 +151,9 @@ handle_keyboard(void) {
 
     // Handle normal keys.
     u8 controller_now = 0;
-    for (size_t i = 0; i < sizeof(input.map); i++) {
+    for (size_t i = 0; i < sizeof(in.map); i++) {
         for (size_t j = 0; j < 8; j++) {
-            char key = input.map[i] & (1 << j);
+            char key = in.map[i] & (1 << j);
             if (key) {
                 char key_code = i * 8 + j;
                 // Normal keys.
@@ -204,15 +257,32 @@ handle_keyboard(void) {
         }
     }
 
-    if (controller_now != input.controller) {
+    if (controller_now != in.controller) {
         devctrl->dat[2] = controller_now;
         uxn_eval(&u, mempeek16(devctrl->dat, 0));
-        input.controller = controller_now;
+        in.controller = controller_now;
     }
 
     // Reset input state.
     devctrl->dat[3] = 0;
-    memset(input.map, 0, sizeof(input.map));
+    memset(in.map, 0, sizeof(in.map));
+}
+
+void
+handle_mouse(void) {
+    if (in.mouse.update) {
+        // TODO: Handle mouse keys
+        mempoke16(devmouse->dat, 0x2, in.mouse.x);
+        mempoke16(devmouse->dat, 0x4, in.mouse.y);
+        uxn_eval(&u, mempeek16(devmouse->dat, 0));
+        in.mouse.update = false;
+    }
+}
+
+void
+handle_input(void) {
+    handle_keyboard();
+    handle_mouse();
 }
 
 void
@@ -430,10 +500,10 @@ main(int argc, char *argv[]) {
     uxn_eval(&u, 0x0100);
     Time frame_time = time_now();
     while (true) {
-        poll_keyboard();
+        poll_input();
         size_t elapsed = time_elapsed(frame_time);
         if (elapsed >= 16666666) {
-            handle_keyboard();
+            handle_input();
 
             // Echo input to standard output.
             uxn_eval(&u, mempeek16(devscreen->dat, 0));