GBA: finish manual lag test

By now, I have added all tests except these five: Shadow sprite,
Stopwatch, Scroll test (Hill zone and Vertical), and the PCM
feature of Sound test.  If I fit them in 31K (6.2K each), I fit
the whole suite in 64K.  Otherwise I have to go compressing stuff.
But it looks like I can release what I have so far to early access.

gba/CHANGES.txt

@@ -1,3 +1,3 @@
-0.01 (2018-06-xx)
-* initial release, with everything but Shadow sprite, Stopwatch,
-  Manual lag, Hill zone scroll, Vertical scroll, and PCM audio test
+0.01 (2018-06-19)
+* initial release, with all tests except Shadow sprite, Stopwatch,
+  Hill zone scroll, Vertical scroll, and PCM in audio test

gba/src/global.h

@@ -89,6 +89,11 @@ void ppu_clear_oam(size_t start);
 void ppu_copy_oam(void);
 void dma_memset16(void *s, unsigned int c, size_t n);
 
+// rand.c
+void lcg_srand(unsigned int in_seed);
+int lcg_rand(void);
+#define LCG_RAND_MAX 65535
+
 // vwfdraw.c
 void loadMapRowMajor(unsigned short *dst, unsigned int tilenum,
                      unsigned int width, unsigned int height);

gba/src/helppages.txt

@@ -15,7 +15,7 @@ Overscan
 ----
 (NYA) Shadow sprite
 (NYA) Stopwatch
-(WIP) Manual lag test
+Manual lag test
 (NYA) Hill zone scroll
 (NYA) Vertical scroll
 Grid scroll
@@ -587,13 +587,11 @@ Select: Show or hide
 
 == 160p Test Suite ==
 
-Ver. 0.00
+Version 0.01 (2018-06-19)
 We're just getting started
 
-© 2011-2016
-  Artemio Urbina
-© 2015-2018
-  Damian Yerrick
+© 2011-2016 Artemio Urbina
+© 2015-2018 Damian Yerrick
 This is free software; see
 the source for copying
 conditions. The program
@@ -627,16 +625,15 @@ You can help:
 Roadmap
 
 0.02: Stopwatch
-0.03: Manual lag test
-0.04: Scroll test
-0.05: Shadow sprite
-0.06: PCM in Sound test
-0.07: Compress under 64 KiB
+0.03: Scroll test
+0.04: Shadow sprite
+0.05: PCM in Sound test
+0.06: Compress under 64 KiB
 ----
 Size watch
 
-As of 0.01, all but 5 tests
-fit in 32 KiB, but some of the
+As of 0.01, all but 4 tests
+fit in 33 KiB, but some of the
 remaining tests are the most
 asset-intensive.
 Should they bust my 64 KiB

gba/src/megaton.c

@@ -2,14 +2,21 @@
 #include <gba_input.h>
 #include <gba_sound.h>
 #include <gba_video.h>
+#include "posprintf.h"
 
 extern const unsigned char helpsect_manual_lag_test[];
 #define PFMAP 23
-#define NUM_PRESSES 10
+#define NUM_TRIALS 10
 #define BLANK_TILE 0x0004
+#define ARROW_TILE 0x0005
+#define CHECKED_TILE 0x0027
+#define UNCHECKED_TILE 0x0026
+#define RETICLE_TILE 0x0028
+#define WORD_OFF 0x0044
+#define WORD_ON 0x0046
 
 // The "On" and "Off" labels must come first because they cause
-// text to be allocated with off at 0x0030 and on at 0x0032
+// text to be allocated with off and on at WORD_OFF and WORD_ON
 static const char megaton_labels[] =
   "\x83""\x88""off\n"
   "\x84""\x90""on\n"
@@ -20,11 +27,39 @@ static const char megaton_labels[] =
   "\x44""\x88""Randomize\n"
   "\x44""\x90""Audio";
 
+static void megaton_draw_boolean(unsigned int y, unsigned int value) {
+  MAP[PFMAP][y][15] = value ? CHECKED_TILE : UNCHECKED_TILE;
+  unsigned int onoff = value ? WORD_ON : WORD_OFF;
+  MAP[PFMAP][y][16] = onoff;
+  MAP[PFMAP][y][17] = onoff + 1;
+}
+
+static void megaton_draw_reticle(unsigned int x, unsigned int y) {
+  unsigned int i = oam_used;
+  y = OBJ_Y(y) | OBJ_16_COLOR | ATTR0_SQUARE;
+  x = OBJ_X(x) | ATTR1_SIZE_16;
+
+  SOAM[i].attr0 = y;
+  SOAM[i].attr1 = x;
+  SOAM[i++].attr2 = RETICLE_TILE;
+  SOAM[i].attr0 = y;
+  SOAM[i].attr1 = x + 16 + OBJ_HFLIP;
+  SOAM[i++].attr2 = RETICLE_TILE;
+  y += 16;
+  SOAM[i].attr0 = y;
+  SOAM[i].attr1 = x + OBJ_VFLIP;
+  SOAM[i++].attr2 = RETICLE_TILE;
+  SOAM[i].attr0 = y;
+  SOAM[i].attr1 = x + 16 + OBJ_HFLIP + OBJ_VFLIP;
+  SOAM[i++].attr2 = RETICLE_TILE;
+  oam_used = i;
+}
+
 void activity_megaton() {
-  signed char lag[NUM_PRESSES] = {-1};
+  signed char lag[NUM_TRIALS] = {-1};
   unsigned int x = 129, xtarget = 160;
   unsigned int with_audio = 1, dir = 1, randomize = 1;
-  unsigned int progress = 0;
+  unsigned int progress = 0, y = 0;
 
   load_common_bg_tiles();
   load_common_obj_tiles();
@@ -34,17 +69,84 @@ void activity_megaton() {
   REG_SOUNDCNT_L = 0xFF77;  // PSG vol/pan
   REG_SOUND1CNT_L = 0x08;   // no sweep
   dma_memset16(MAP[PFMAP], BLANK_TILE, 32*20*2);
-  vwfDrawLabels(megaton_labels, PFMAP, 0x30);
+  vwfDrawLabels(megaton_labels, PFMAP, 0x44);
+
+  // Draw stationary reticle
+  for (unsigned int y = 0; y < 2; ++y) {
+    for (unsigned int x = 0; x < 2; ++x) {
+      unsigned int t = 0x0028 + y * 2 + x;
+      MAP[PFMAP][7+y][13+x] = t;
+      MAP[PFMAP][7+y][16-x] = t ^ 0x400;
+      MAP[PFMAP][10-y][13+x] = t ^ 0x800;
+      MAP[PFMAP][10-y][16-x] = t ^ 0xC00;
+    }
+  }
+
+  // Make space for results
+  dma_memset16(PATRAM4(0, 0x30), 0x0000, 32 * 20);
+  loadMapRowMajor(&(MAP[PFMAP][2][2]), 0x30, 2, 10);
 
   do {
     read_pad_help_check(helpsect_manual_lag_test);
 
-    if (new_keys && KEY_B) {
+    if (new_keys & KEY_B) {
       break;
     }
+    if (new_keys & KEY_A) {
+      signed int diff = x - 128;
+      if (xtarget < 128) diff = -diff;
+      unsigned int early = diff < 0;
+      unsigned int value = early ? -diff : diff;
+      uint32_t *tileaddr = PATRAM4(0, 0x30 + progress * 2);
+      dma_memset16(tileaddr, 0x0000, 32 * 2);
+      if (early) {
+        vwf8PutTile(tileaddr, 'E', 0, 1);
+      }
+      unsigned int tens = value / 10;
+      if (tens) {
+        vwf8PutTile(tileaddr, tens + '0', 6, 1);
+      }
+      vwf8PutTile(tileaddr, (value - tens * 10) + '0', 11, 1);
+      if (!early && value <= 25) lag[progress++] = value;
+    }
+    REG_SOUND2CNT_L = ((new_keys & KEY_A) && with_audio) ? 0xA080 : 0x0000;
+    REG_SOUND2CNT_H = (2048 - 262) | 0x8000;
+    if ((new_keys & KEY_UP) && y > 0) {
+      --y;
+    }
+    if ((new_keys & KEY_DOWN) && y < 2) {
+      ++y;
+    }
+    if (new_keys & (KEY_LEFT | KEY_RIGHT)) {
+      switch (y) {
+        case 0:  // change direction
+        dir += (new_keys & KEY_LEFT) ? 2 : 1;
+        if (dir > 3) dir -= 3;
+        break;
+        case 1:
+        randomize = !randomize;
+        break;
+        case 2:
+        with_audio = !with_audio;
+        break;
+      }
+    }
 
+    // Move reticle
+    x += (xtarget > x) ? 1 : -1;
+    if (x == xtarget) {
+      xtarget = 36 + 128;
+      if (randomize) xtarget += (lcg_rand() >> 12) - 8;
+      if (x > 128) xtarget = 256 - xtarget;
+    }
+
     oam_used = 0;
-    // Draw sprites
+    if (dir & 0x01) {
+      megaton_draw_reticle(104 + x - 128, 56);
+    }
+    if (dir & 0x02) {
+      megaton_draw_reticle(104, 56 + x - 128);
+    }
     ppu_clear_oam(oam_used);
 
     VBlankIntrWait();
@@ -53,12 +155,49 @@ void activity_megaton() {
     BG_OFFSET[0].x = BG_OFFSET[0].y = 0;
     BG_COLORS[0] = (x == 128 && with_audio) ? RGB5(31, 31, 31) : RGB5(0, 0, 0);
     BG_COLORS[1] = OBJ_COLORS[1] = RGB5(31, 31, 31);
+    BG_COLORS[2] = RGB5(20, 25, 31);
     ppu_copy_oam();
 
-  } while (!(new_keys & KEY_B));
+    // Draw the cursor
+    for (unsigned int i = 0; i < 3; ++i) {
+      unsigned int tilenum = (i == y) ? ARROW_TILE : BLANK_TILE;
+      MAP[PFMAP][i + 16][7] = tilenum;
+    }
+    MAP[PFMAP][16][15] = (dir & 0x01) ? CHECKED_TILE : UNCHECKED_TILE;
+    MAP[PFMAP][16][19] = (dir & 0x02) ? CHECKED_TILE : UNCHECKED_TILE;
+    megaton_draw_boolean(17, randomize);
+    megaton_draw_boolean(18, with_audio);
+
+    // TODO: beep
+    REG_SOUND1CNT_H = (x == 128 && with_audio) ? 0xA080 : 0x0000;
+    REG_SOUND1CNT_X = (2048 - 131) | 0x8000;
+  } while (!(new_keys & KEY_B) && (progress < NUM_TRIALS));
+
   BG_COLORS[0] = RGB5(0, 0, 0);
   REG_SOUNDCNT_X = 0;  // reset audio
+  if (progress < 10) return;
+
+  // Display average: First throw away all labels below Y=120
+  dma_memset16(MAP[PFMAP][15], BLANK_TILE, 32*4*2);
+
+  unsigned int sum = 0;
+  for (unsigned int i = 0; i < NUM_TRIALS; ++i) {
+    sum += lag[i];
+  }
+  unsigned int whole_frames = sum / NUM_TRIALS;
+  posprintf(help_line_buffer, "\x40\x80""Average lag: %d.%d frames",
+            whole_frames, sum - whole_frames * NUM_TRIALS);
+  vwfDrawLabels(help_line_buffer, PFMAP, 0x44);
+
+  // Ignore spurious presses
+  for (unsigned int i = 20; i > 0; --i) {
+    VBlankIntrWait();
+  }
 
-  if (new_keys && KEY_B) return;
+  do {
+    VBlankIntrWait();
+    read_pad();
+  } while (!new_keys);
 
+  // TODO: Display average lag
 }

gba/src/rand.c

@@ -0,0 +1,15 @@
+#include "global.h"
+
+// This uses the same linear congruential generator as cc65's
+// random function, but with different tempering.
+
+static unsigned int seed = 1;
+
+void lcg_srand(unsigned int in_seed) {
+  seed = in_seed;
+}
+
+int lcg_rand(void) {
+  seed = (seed * 0x01010101) + 0x31415927;
+  return (seed ^ (seed >> 16)) & 0xFFFF;
+}