From 16167bc599b40f6c3c203414c57c07381eb85055 Mon Sep 17 00:00:00 2001
From: Andy Sloane <andy@a1k0n.net>
Date: Wed, 28 Oct 2015 16:21:12 -0700
Subject: [PATCH] implement pattern / song jumps

---
 index.html |  3 +--
 xm.js      | 25 ++++++++++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/index.html b/index.html
index e895b92..ab59860 100644
--- a/index.html
+++ b/index.html
@@ -14,9 +14,8 @@ todo:
  - instrument fadeout
  - missing XM effects (in rough order of priority):
    - Rxy - retrigger
-   - Bxx / Dxx - position / pattern jumps
-   - 7xy - tremolo
    - E3x, E4x, E5x, E6x, E7x, E9x, EDx, EEx
+   - 7xy - tremolo
    - Gxx, Hxy, Kxx, Lxx, Pxy, Txy
  - oscilloscopes
 </pre>
diff --git a/xm.js b/xm.js
index 260cfe0..188bbe9 100644
--- a/xm.js
+++ b/xm.js
@@ -473,10 +473,25 @@ function eff_t0_a(ch, data) {  // volume slide
   }
 }
 
+function eff_t0_b(ch, data) {  // song jump (untested)
+  if (data < songpats.length) {
+    cur_songpos = data
+    cur_pat = songpats[cur_songpos];
+  }
+}
+
 function eff_t0_c(ch, data) {  // set volume
   ch.vol = data & 0x3f;
 }
 
+function eff_t0_d(ch, data) {  // pattern jump
+  cur_songpos++;
+  if (cur_songpos >= songpats.length)
+    cur_songpos = song_looppos;
+  cur_pat = songpats[cur_songpos];
+  cur_row = data;
+}
+
 function eff_t0_e(ch, data) {  // extended effects!
   var eff = data >> 4;
   data = data & 0x0f;
@@ -537,9 +552,9 @@ var effects_t0 = [  // effect functions on tick 0
   eff_t0_8,  // 8
   eff_t0_9,  // 9
   eff_t0_a,  // a
-  eff_unimplemented_t0,  // b
+  eff_t0_b,  // b
   eff_t0_c,  // c
-  eff_unimplemented_t0,  // d
+  eff_t0_d,  // d
   eff_t0_e,  // e
   eff_t0_f,  // f
 ];
@@ -622,11 +637,11 @@ var effects_t1 = [  // effect functions on tick 1+
   eff_nop,   // 8
   eff_nop,   // 9
   eff_t1_a,  // a
-  eff_unimplemented,  // b
+  eff_nop,   // b
   eff_nop,   // c
-  eff_unimplemented,  // d
+  eff_nop,   // d
   eff_t1_e,  // e
-  eff_unimplemented,  // f
+  eff_nop,   // f
 ];
 
 function ConvertSample(array, bits) {