From 8236e0a7d4f99d1d354b3c7667327e707f1f2f4c Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Sat, 22 Jul 2023 10:08:20 +0200
Subject: Add trig probability

---
 src/main.c      |  4 ++--
 src/rng.c       |  4 +++-
 src/sequencer.c | 25 +++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/main.c b/src/main.c
index ffe60e4..a6c2238 100644
--- a/src/main.c
+++ b/src/main.c
@@ -15,9 +15,9 @@ WITH REGARD TO THIS SOFTWARE.
 //  + Add new UI for the parameter pages
 //  + Change cursor drawing for new parameter pages
 //  + Change cursor behaviour for new parameter pages
+//  + Allow prob control (% based or 1:2, etc.)
 //  - Display notification when editing a parameter with the highest priority
 //  - Add panning support.
-//  - Allow prob control (% based or 1:2, etc.)
 //  - Add custom user themes
 //  - Animations for cursor movement/current step highlight. (A fade out maybe?)
 //
@@ -29,7 +29,7 @@ WITH REGARD TO THIS SOFTWARE.
 //  - Undo/Redo.
 //
 //  Advanced
-//  - Per trig note probability.
+//  + Per trig note probability.
 //  - Add tap tempo for BPM.
 //  - Allow "marking" several trigs to be able to copy/paste them and/or adjust
 //    their parameters.
diff --git a/src/rng.c b/src/rng.c
index 58a517b..4a93562 100644
--- a/src/rng.c
+++ b/src/rng.c
@@ -7,7 +7,9 @@ u32 hash16(u32 input, u32 key) {
 
 u16 rng16() {
     rng_state += 0xbadd;
-    return hash16(rng_state, 0x10de);
+    u32 ret = hash16(rng_state, 0x10de);
+    rng_state += ret;
+    return ret;
 }
 
 u32 rng32() {
diff --git a/src/sequencer.c b/src/sequencer.c
index 00baebb..e017700 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -17,6 +17,7 @@ bool redraw_params = true;
 bool redraw_bpm = true;
 bool redraw_piano_note = true;
 bool update_bpm = false;
+u8 bar_counter = 0;
 
 void
 gate_off(void) {
@@ -73,6 +74,25 @@ find_prev_pattern(void) {
 
 bool
 should_play(u8 prob) {
+    switch (prob) {
+        case PROB_100:         { return true; } break;
+        case PROB_80:          { return rng16() < 52427; } break;
+        case PROB_60:          { return rng16() < 39320; } break;
+        case PROB_40:          { return rng16() < 26213; } break;
+        case PROB_20:          { return rng16() < 13106; } break;
+        case PROB_FIRST:       { return bar_counter == 0; } break;
+        case PROB_NOT_FIRST:   { return bar_counter != 0; } break;
+        case PROB_ONE_TWO:     { return bar_counter % 2 == 0; } break;
+        case PROB_TWO_TWO:     { return bar_counter % 2 == 1; } break;
+        case PROB_ONE_THREE:   { return bar_counter % 3 == 0; } break;
+        case PROB_TWO_THREE:   { return bar_counter % 3 == 1; } break;
+        case PROB_THREE_THREE: { return bar_counter % 3 == 2; } break;
+        case PROB_ONE_FOUR:    { return bar_counter % 4 == 0; } break;
+        case PROB_TWO_FOUR:    { return bar_counter % 4 == 1; } break;
+        case PROB_THREE_FOUR:  { return bar_counter % 4 == 2; } break;
+        case PROB_FOUR_FOUR:   { return bar_counter % 4 == 3; } break;
+        default: break;
+    }
     return true;
 }
 
@@ -246,6 +266,9 @@ play_step(void) {
         case SYNC_OUT_LINK_AUDIO_4: { if (step_counter % 4 == 0) { gate_on(); audio_sync_click = true; } } break;
         default: break;
     }
+    if (step_counter == 15) {
+        bar_counter++;
+    }
     step_counter = (step_counter + 1) % 16;
     redraw_piano_note = true;
 }
@@ -389,6 +412,7 @@ stop_playing(void) {
     chain.current = 15;
     chain.current = find_next_pattern();
     chain.playing = false;
+    bar_counter = 0;
     stop_sound();
 }
 
@@ -399,6 +423,7 @@ toggle_playing(void) {
     chain.current = 15;
     chain.current = find_next_pattern();
     chain.playing = false;
+    bar_counter = 0;
     if (current_pattern == next_pattern && chain.len > 0) {
         chain.playing = true;
         next_pattern = chain.chain[chain.current];
-- 
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