From 01a0849d23c413f9328e2a9444dc38a4d7606b36 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Tue, 4 Apr 2023 12:06:37 +0200
Subject: Add bank selection and reload previous saved state

---
 src/sequencer.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 94 insertions(+), 4 deletions(-)

(limited to 'src/sequencer.c')

diff --git a/src/sequencer.c b/src/sequencer.c
index c4a1d2a..3b77adb 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -1,10 +1,23 @@
 #include "rng.c"
 #include "text.h"
 
+void
+sram_read(u8 *dst, u16 pos, u16 n_bytes) {
+    for (size_t i = 0; i < n_bytes; ++i) {
+        dst[i] = SRAM[pos + i];
+    }
+}
+
+void
+sram_write(u8 *src, u16 pos, u16 n_bytes) {
+    for (size_t i = 0; i < n_bytes; ++i) {
+        SRAM[pos + i] = src[i];
+    }
+}
+
 // TODO
 //  - Preview sound keys?
 //  - Copy paste trigs/notes/params
-//  - Different banks for storing patterns
 //  - Finish noise channel (parameter editing)
 void set_time(int bpm);
 
@@ -429,6 +442,15 @@ const ChannelNoise default_ch4 = {
     .active = true,
 };
 
+typedef struct Metadata {
+    u8 blank;
+    u32 magic;
+    int current_bank;
+    int current_pattern;
+} Metadata;
+
+static Metadata metadata = {0};
+
 typedef struct Pattern {
     ChannelSquare ch1;
     ChannelSquare ch2;
@@ -449,6 +471,16 @@ static Pattern patterns[8] = {
     {default_ch1, default_ch2, default_ch3, default_ch4, default_bpm, 0},
 };
 
+void
+save_bank(int i) {
+    sram_write(&patterns, sizeof(Metadata) + i * sizeof(patterns), sizeof(patterns));
+}
+
+void
+load_bank(int i) {
+    sram_read(&patterns, sizeof(Metadata) + i * sizeof(patterns), sizeof(patterns));
+}
+
 //
 // Channel render functions.
 //
@@ -1861,23 +1893,64 @@ handle_right_col_selection(void) {
             case R_COL_PLAY: {
                 pause_playing();
             } break;
-            // TODO: stop playing
-            // TODO: reset cursors if applicable
-            // TODO: load bank from sram
             case R_COL_BANK_A: {
+                stop_playing();
+                save_bank(current_bank);
+                metadata.current_pattern = current_pattern;
+                metadata.current_bank = 0;
+                sram_write(&metadata, 0, sizeof(Metadata));
+                if (current_bank != 0) {
+                    load_bank(0);
+                }
                 current_bank = 0;
+                draw_pattern_buttons();
+                draw_triggers();
+                draw_channels();
                 draw_bank_buttons();
             } break;
             case R_COL_BANK_B: {
+                stop_playing();
+                save_bank(current_bank);
+                metadata.current_pattern = current_pattern;
+                metadata.current_bank = 1;
+                sram_write(&metadata, 0, sizeof(Metadata));
+                if (current_bank != 1) {
+                    load_bank(1);
+                }
                 current_bank = 1;
+                draw_pattern_buttons();
+                draw_triggers();
+                draw_channels();
                 draw_bank_buttons();
             } break;
             case R_COL_BANK_C: {
+                stop_playing();
+                save_bank(current_bank);
+                metadata.current_pattern = current_pattern;
+                metadata.current_bank = 2;
+                sram_write(&metadata, 0, sizeof(Metadata));
+                if (current_bank != 2) {
+                    load_bank(2);
+                }
                 current_bank = 2;
+                draw_pattern_buttons();
+                draw_triggers();
+                draw_channels();
                 draw_bank_buttons();
             } break;
             case R_COL_BANK_D: {
+                stop_playing();
+                save_bank(current_bank);
+                metadata.current_pattern = current_pattern;
+                metadata.current_bank = 3;
+                sram_write(&metadata, 0, sizeof(Metadata));
+                if (current_bank != 3) {
+                    load_bank(3);
+                }
                 current_bank = 3;
+                draw_pattern_buttons();
+                draw_triggers();
+                draw_channels();
                 draw_bank_buttons();
             } break;
         }
@@ -2533,6 +2606,23 @@ sequencer_init(void) {
     // Unpack non-sprite tiles directly on the VRAM.
     load_assets();
 
+    // Load the previous bank from SRAM or initialize it if needed.
+    sram_read(&metadata, 0, sizeof(Metadata));
+    if (metadata.magic != 0xbadd10de) {
+        metadata.magic = 0xbadd10de;
+        sram_write(&metadata, 0, sizeof(Metadata));
+        save_bank(0);
+        save_bank(1);
+        save_bank(2);
+        save_bank(3);
+    } else {
+        current_bank = metadata.current_bank;
+        current_pattern = metadata.current_pattern;
+        next_pattern = metadata.current_pattern;
+        pattern_selection_loc = current_pattern;
+        load_bank(metadata.current_bank);
+    }
+
     // Initialize background objects and sprites.
     draw_triggers();
     draw_channels();
-- 
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