From 927886b7f362eacb434215424bc7eff89d3cbc26 Mon Sep 17 00:00:00 2001
From: Max Regan <mgregan2@gmail.com>
Date: Mon, 10 Sep 2018 22:09:42 -0700
Subject: [PATCH] cpu: pass blargg cpu tests 1,3-9

---
 src/gbemu/cpu.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/gbemu/cpu.c b/src/gbemu/cpu.c
index f70f274..c1ff4b3 100644
--- a/src/gbemu/cpu.c
+++ b/src/gbemu/cpu.c
@@ -557,8 +557,37 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		LD_D8(cpu, cpu->h);
 		break;
 	case 0x27: /* DAA */
-		/* TODO: DAA */
+	{
+		/* The internet agrees that this opcode is terrible. I've
+		 * copied the same implementation (almost) everyone else
+		 * has. */
+		uint16_t a = cpu->a;
+		if (!cpu->nf) {
+			if (cpu->hf || ((a & 0xf) > 9)) {
+				a += 0x6;
+			}
+			if (cpu->cf || (a > 0x9f)) {
+				a += 0x60;
+			}
+		} else {
+			if (cpu->hf) {
+				a -= 0x6;
+				a &= 0xff;
+			}
+			if (cpu->cf) {
+				a -= 0x60;
+			}
+		}
+
+		if (GET_BIT(a,8)) {
+			cpu->cf = 1;
+		}
+
+		cpu->hf = 0;
+		cpu->a = a;
+		cpu->zf = !cpu->a;
 		break;
+	}
 	case 0x28: /* JR Z, r8 */
 		if (cpu->zf) {
 			JR_8(cpu);
@@ -1631,7 +1660,9 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		ASSERT(0);
 		break;
 	case 0xde: /* SBC A, d8 */
-		ASSERT(0);
+		val = gb_mem_read(cpu->memory, cpu->pc++);
+		SBC_8(cpu, cpu->a, val);
+		break;
 	case 0xdf: /* RST 0x18 */
 		RST(cpu, 0x18);
 		break;