From c0262cba634348097555a54f753cd7329d39da95 Mon Sep 17 00:00:00 2001
From: Max Regan <mgregan2@gmail.com>
Date: Tue, 28 Aug 2018 22:39:36 -0700
Subject: [PATCH] cpu: get blargh cpu test 3 passing

---
 gbdb_boot_test  |  2 +-
 src/gbemu/cpu.c | 41 +++++++++++++++++++++++++++++++++--------
 2 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/gbdb_boot_test b/gbdb_boot_test
index f52f7e1..2c21517 100644
--- a/gbdb_boot_test
+++ b/gbdb_boot_test
@@ -25,7 +25,7 @@ assert $hl == 0x9ffe
 step
 
 assert $pc == 10
-assert $f == 0x2
+assert $f == 0x20
 step
 
 runto 0xc
diff --git a/src/gbemu/cpu.c b/src/gbemu/cpu.c
index 18fe0eb..f2f2f55 100644
--- a/src/gbemu/cpu.c
+++ b/src/gbemu/cpu.c
@@ -22,6 +22,10 @@
 #define CALC_H_ADD(a, b) ((((a) & 0xf) + ((b) & 0xf)) > 0xf)
 #define CALC_H_SUB(a, b) (((a) & 0xf) < ((b) & 0xf))
 
+#define CARRY_MASK(idx) ((1 << idx) - 1)
+#define ADD_CARRY(a, b, idx) \
+	((((a) & CARRY_MASK(idx)) + ((b) & CARRY_MASK(idx))) > CARRY_MASK(idx))
+
 #define CALC_C_ADD_16(a, b) (0xffff - (a) < (b))
 #define CALC_C_ADD_8(a, b) (0xff - (a) < (b))
 #define CALC_C_SUB(a, b) ((a) < (b))
@@ -400,8 +404,10 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		WRITE_BIT(cpu->a, 0, cpu->cf);
 		break;
 	case 0x08: /* LD (a16), SP */
-		cpu->sp = gb_mem_read(cpu->memory, cpu->pc++);
-		cpu->sp |= gb_mem_read(cpu->memory, cpu->pc++) << 8;
+		val_16 = gb_mem_read(cpu->memory, cpu->pc++);
+		val_16 |= gb_mem_read(cpu->memory, cpu->pc++) << 8;
+		gb_mem_write(cpu->memory, val_16, cpu->sp & 0xff);
+		gb_mem_write(cpu->memory, val_16 + 1, (cpu->sp >> 8) & 0xff);
 		break;
 	case 0x09: /* ADD HL, BC */
 		ADD_16(cpu, cpu->hl, cpu->bc);
@@ -1538,8 +1544,17 @@ int lr35902_cycle(struct lr35902_state *cpu)
 	case 0xe7: /* RST 0x20 */
 		RST(cpu, 0x20);
 		break;
-	case 0xe8:
-		ASSERT(0);
+	case 0xe8: /* ADD SP, r8 */
+		val_16 = gb_mem_read(cpu->memory, cpu->pc++);
+		if (val_16 & 0x80) {
+			val_16 |= 0xff00;
+		}
+		cpu->cf = ADD_CARRY(cpu->sp, val_16, 8);
+		cpu->hf = ADD_CARRY(cpu->sp, val_16, 4);
+		cpu->zf = 0;
+		cpu->nf = 0;
+		cpu->sp += val_16;
+		break;
 	case 0xe9: /* JP (hl) */
 		cpu->pc = cpu->hl;
 		break;
@@ -1597,9 +1612,19 @@ int lr35902_cycle(struct lr35902_state *cpu)
 	case 0xf7: /* RST 0x30 */
 		RST(cpu, 0x30);
 		break;
-	case 0xf8:
-	case 0xf9:
-		ASSERT(0);
+	case 0xf8: /* LD HL, SP+r8 */
+		val_16 = gb_mem_read(cpu->memory, cpu->pc++);
+		if (val_16 & 0x80) {
+			val_16 |= 0xff00;
+		}
+		cpu->cf = ADD_CARRY(cpu->sp, val_16, 8);
+		cpu->hf = ADD_CARRY(cpu->sp, val_16, 4);
+		cpu->zf = 0;
+		cpu->nf = 0;
+		cpu->hl = cpu->sp + val_16;
+		break;
+	case 0xf9: /* LD SP, HL */
+		cpu->sp = cpu->hl;
 		break;
 	case 0xfa:
 		val_16 = gb_mem_read(cpu->memory, cpu->pc++);
@@ -1607,7 +1632,7 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		cpu->a = gb_mem_read(cpu->memory, val_16);
 		break;
 	case 0xfb: /* EI */
-		gb_log0("Interrupts ON\n");
+		gb_log("Interrupts ON\n");
 		break;
 	case 0xfc: /* UNDEF */
 		ASSERT(0);