Move fft-test into tests/ directory

tests/fft.c

@@ -0,0 +1,69 @@
+#define FFT_WRITE_LANE  0x2000
+#define FFT_RD_LANE_BASE 0x2008
+// addr of read lane i is FFT_RD_LANE_BASE + i * 8
+
+#include <stdio.h>
+#include <inttypes.h>
+#include <math.h>
+
+// from test_pts.py
+// point size (and therefore integer width/uint32_t) determined by IOWidth from Tail.scala
+// point size is 2 * IOWidth since both real and imaginary components get IOWidth bits
+const uint32_t points[8] = {
+  0b00000000101101011111111101001011, // 00B5FF4B
+  0b00000000000000001111111100000000, // 0000FF00
+  0b11111111010010111111111101001011, // FF4BFF4B
+  0b11111111000000000000000000000000, // FF000000
+  0b11111111010010110000000010110101, // FF4B00B5
+  0b00000000000000000000000100000000, // 00000100
+  0b00000000101101010000000010110101, // 00B500B5
+  0b00000001000000000000000000000000  // 01000000
+};
+
+const uint32_t expected_outputs[8] = {
+  0x00000000, // read 0
+  0x00000000, // read 1
+  0x00000000, // read 2
+  0xffff0000, // read 3
+  0x00000000, // read 4 -- real portion is 0xff (very small negative number)
+  0x00000000, // read 5
+  0x00000000, // read 6
+  0x05a8fa57, // read 7 -- real: ~5.656 imaginary: ~-5.656
+};
+
+int main(void) {
+  int num_points = 8;
+
+  // write points to fft
+  for (int i = 0; i < num_points; i++) {
+    uint32_t write_val = points[i];
+    volatile uint32_t* ptr = (volatile uint32_t*) FFT_WRITE_LANE;
+    *ptr = write_val;
+  }
+
+  for (int i = 0; i < num_points; i++) {
+    volatile uint32_t* ptr_0 = (volatile uint32_t*) (FFT_RD_LANE_BASE + (i * 8));
+    uint32_t read_val = *ptr_0;
+
+    /* To convert binary to floating point
+     * However, RISC-V compiler can't print floats. You can use this by copy-pasting it into an online
+     * C compiler. The printf at the bottom of this for loop will print out the values of real_part_bin
+     * and imag_part_bin
+     *
+     * Code is commented out because default risc-v compiler doesn't support pow
+     */
+    // uint16_t real_part_bin = read_val >> 16;
+    // uint16_t imag_part_bin = read_val & 0xFFFF;
+    // int bp = 8; // from tail.scala
+    // float real_comp = ((int16_t) real_part_bin) * pow(2, bp);
+    // float imag_comp = ((int16_t) imag_part_bin) * pow(2, bp);
+
+    if (read_val != expected_outputs[i]) {
+      printf("FAIL: Expected and real differed: %x %x", read_val, expected_outputs[i]);
+      return -1;
+    }
+  }
+
+  printf("PASS: FFT Test Passed\n");
+  return 0;
+}