RGBMatrix: Additional tile tweaks

 * Introduce explicit serpentine: bool argument instead of using negative
   numbers (thanks, ghost of @tannewt sitting on one shoulder)
 * Fix several calculations of height

Testing performed (matrixportal):
 * set up a serpentine 64x64 virtual display with 2 64x32 tiles
 * tried all 4 rotations
 * looked at output of REPL

2 files changed, 7 insertions, 4 deletions

diff --git a/shared-module/rgbmatrix/RGBMatrix.c b/shared-module/rgbmatrix/RGBMatrix.c
index 95a7eda75..4318604c6 100644
--- a/shared-module/rgbmatrix/RGBMatrix.c
+++ b/shared-module/rgbmatrix/RGBMatrix.c
@@ -42,7 +42,7 @@
 
 extern Protomatter_core *_PM_protoPtr;
 
-void common_hal_rgbmatrix_rgbmatrix_construct(rgbmatrix_rgbmatrix_obj_t *self, int width, int bit_depth, uint8_t rgb_count, uint8_t *rgb_pins, uint8_t addr_count, uint8_t *addr_pins, uint8_t clock_pin, uint8_t latch_pin, uint8_t oe_pin, bool doublebuffer, mp_obj_t framebuffer, int8_t tile, void *timer) {
+void common_hal_rgbmatrix_rgbmatrix_construct(rgbmatrix_rgbmatrix_obj_t *self, int width, int bit_depth, uint8_t rgb_count, uint8_t *rgb_pins, uint8_t addr_count, uint8_t *addr_pins, uint8_t clock_pin, uint8_t latch_pin, uint8_t oe_pin, bool doublebuffer, mp_obj_t framebuffer, int8_t tile, bool serpentine, void *timer) {
     self->width = width;
     self->bit_depth = bit_depth;
     self->rgb_count = rgb_count;
@@ -54,6 +54,7 @@ void common_hal_rgbmatrix_rgbmatrix_construct(rgbmatrix_rgbmatrix_obj_t *self, i
     self->latch_pin = latch_pin;
     self->doublebuffer = doublebuffer;
     self->tile = tile;
+    self->serpentine = serpentine;
 
     self->timer = timer ? timer : common_hal_rgbmatrix_timer_allocate();
     if (self->timer == NULL) {
@@ -61,7 +62,7 @@ void common_hal_rgbmatrix_rgbmatrix_construct(rgbmatrix_rgbmatrix_obj_t *self, i
     }
 
     self->width = width;
-    self->bufsize = 2 * width * rgb_count / 3 * (1 << addr_count);
+    self->bufsize = 2 * width * rgb_count / 3 * (1 << addr_count) * tile;
 
     common_hal_rgbmatrix_rgbmatrix_reconstruct(self, framebuffer);
 }
@@ -96,7 +97,8 @@ void common_hal_rgbmatrix_rgbmatrix_reconstruct(rgbmatrix_rgbmatrix_obj_t* self,
         self->rgb_count/6, self->rgb_pins,
         self->addr_count, self->addr_pins,
         self->clock_pin, self->latch_pin, self->oe_pin,
-        self->doublebuffer, self->tile, self->timer);
+        self->doublebuffer, self->serpentine ? -self->tile : self->tile,
+        self->timer);
 
     if (stat == PROTOMATTER_OK) {
         _PM_protoPtr = &self->protomatter;
@@ -210,7 +212,7 @@ int common_hal_rgbmatrix_rgbmatrix_get_width(rgbmatrix_rgbmatrix_obj_t* self) {
 }
 
 int common_hal_rgbmatrix_rgbmatrix_get_height(rgbmatrix_rgbmatrix_obj_t* self) {
-    int computed_height = (self->rgb_count / 3) << (self->addr_count);
+    int computed_height = (self->rgb_count / 3) * (1 << (self->addr_count)) * self->tile;
     return computed_height;
 }
 
diff --git a/shared-module/rgbmatrix/RGBMatrix.h b/shared-module/rgbmatrix/RGBMatrix.h
index 7fce73c8b..4a0e9235e 100644
--- a/shared-module/rgbmatrix/RGBMatrix.h
+++ b/shared-module/rgbmatrix/RGBMatrix.h
@@ -44,5 +44,6 @@ typedef struct {
     bool core_is_initialized;
     bool paused;
     bool doublebuffer;
+    bool serpentine;
     int8_t tile;
 } rgbmatrix_rgbmatrix_obj_t;