Add the 74HC595 Snake game project

08-74HC595-Snake/matrix.cpp

@@ -0,0 +1,56 @@
+#include <Arduino.h>
+#include <stdint.h>
+#include "error.h"
+#include "IC74HC595.h"
+#include "matrix.h"
+
+uint8_t matrixcolumns[8] = {0};
+
+int pokeMatrixPixel(uint8_t x, uint8_t y)
+{
+    if (x > 7 || y > 7) {
+	ERROR(ERRNO_OUTOFBOUNDS);
+    }
+    // Because of the alignment of the screen in our demo, we treat columns as the X axis
+    matrixcolumns[x] = matrixcolumns[x] | (1 << y);
+    return ERRNO_SUCCESS;
+}
+
+void resetMatrix()
+{
+    matrixcolumns[0] = 0;
+    matrixcolumns[1] = 0;
+    matrixcolumns[2] = 0;
+    matrixcolumns[3] = 0;
+    matrixcolumns[4] = 0;
+    matrixcolumns[5] = 0;
+    matrixcolumns[6] = 0;
+    matrixcolumns[7] = 0;
+}
+
+void displayMatrix()
+{
+    for (int i = 0; i < 8; i++) {
+	writeLEDMatrix(matrixcolumns[i], ~(1 << i));
+    }
+}
+
+void writeLEDMatrix(uint8_t row, uint8_t col)
+{
+    digitalWrite(matrixcols.updatepin, LOW);
+    shiftOut(matrixcols.datapin, matrixcols.clockpin, LSBFIRST, row);
+    shiftOut(matrixcols.datapin, matrixcols.clockpin, MSBFIRST, col);
+    digitalWrite(matrixcols.updatepin, HIGH);
+}
+
+void testMatrix()
+{
+    uint8_t row = 0;
+    uint8_t col = 0;
+    for ( int i = 0; i < 8; i++ ) {
+	row = (1 << i);
+	col = ~(1 << i);
+	Serial.printf("%d = (%d, %d)\n", i, row, col);
+	writeLEDMatrix(row, col);
+    }
+};