From 5ed288eaa957bbfea229a341bf366f31a4de7614 Mon Sep 17 00:00:00 2001
From: Matthew Laux <matthew.laux@gmail.com>
Date: Wed, 18 Oct 2023 17:14:20 -0500
Subject: [PATCH] not really sure what i was working on

---
 cli/save.sav | Bin 0 -> 32768 bytes
 src/cpu.c    |  32 +++++++++++++++++++++++++++++++-
 src/dmg.c    |   3 ++-
 3 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 cli/save.sav

diff --git a/cli/save.sav b/cli/save.sav
new file mode 100644
index 0000000000000000000000000000000000000000..aa3652cab5c6bc0e60ca36ccfdbde92b8ab702cd
GIT binary patch
literal 32768
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literal 0
HcmV?d00001

diff --git a/src/cpu.c b/src/cpu.c
index 2b75c19..88b4379 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -356,6 +356,32 @@ static void add16(struct cpu *cpu, u16 src)
     write_hl(cpu, trunc);
 }
 
+static void add_sp(struct cpu *cpu, u8 value)
+{
+    int total = cpu->sp + (signed char) value;
+    clear_flag(cpu, FLAG_ZERO);
+    clear_flag(cpu, FLAG_SIGN);
+    if (total > 0xffff) {
+        set_flag(cpu, FLAG_CARRY);
+    } else {
+        clear_flag(cpu, FLAG_CARRY);
+    }
+    cpu->sp = (u16) total;
+}
+
+static void ld_hl_sp(struct cpu *cpu, u8 value)
+{
+    int total = cpu->sp + (signed char) value;
+    clear_flag(cpu, FLAG_ZERO);
+    clear_flag(cpu, FLAG_SIGN);
+    if (total > 0xffff) {
+        set_flag(cpu, FLAG_CARRY);
+    } else {
+        clear_flag(cpu, FLAG_CARRY);
+    }
+    write_hl(cpu, total);
+}
+
 static u8 read_reg(struct cpu *cpu, int index)
 {
     switch (index) {
@@ -1026,6 +1052,10 @@ void cpu_step(struct cpu *cpu)
         case 0xe5: // PUSH HL
             push(cpu, read_hl(cpu));
             break;
+        case 0xe8:
+            add_sp(cpu, read8(cpu, cpu->pc));
+            cpu->pc++;
+            break;
         case 0xe9: // JP HL
             cpu->pc = read_hl(cpu);
             break;
@@ -1051,7 +1081,7 @@ void cpu_step(struct cpu *cpu)
             push(cpu, read_af(cpu));
             break;
         case 0xf8: // LD HL, SP+i8
-            write_hl(cpu, cpu->sp + (signed) read8(cpu, cpu->pc));
+            ld_hl_sp(cpu, read8(cpu, cpu->pc));
             cpu->pc++;
             break;
         case 0xf9: // LD SP, HL
diff --git a/src/dmg.c b/src/dmg.c
index b4f6b3d..e9d95b2 100644
--- a/src/dmg.c
+++ b/src/dmg.c
@@ -263,6 +263,7 @@ static void render_objs(struct dmg *dmg)
 static void timer_step(struct dmg *dmg)
 {
     dmg->timer_div++;
+    return;
 
     if (!(dmg_read(dmg, REG_TIMER_CONTROL) & TIMER_CONTROL_ENABLED)) {
         return;
@@ -290,7 +291,7 @@ void dmg_step(void *_dmg)
     // order of dependencies? i think cpu needs to step first then update
     // all other hw
     cpu_step(dmg->cpu);
-    //timer_step(dmg);
+    timer_step(dmg);
 
     // each line takes 456 cycles
     int cycle_diff = dmg->cpu->cycle_count - dmg->last_lcd_update;