From 1efe2b579d1c78a5b8050feca39d7d12d69731eb Mon Sep 17 00:00:00 2001
From: Ben Kurtovic <ben.kurtovic@gmail.com>
Date: Sun, 24 Apr 2016 01:57:09 -0500
Subject: [PATCH] Add POP; fix bugs involving relative jumps and PUSH.

---
 src/z80.c            | 10 ++++++++++
 src/z80_ops.inc.c    | 18 ++++++++++++++----
 src/z80_tables.inc.c |  8 ++++----
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/src/z80.c b/src/z80.c
index 88e159f..5f76e7b 100644
--- a/src/z80.c
+++ b/src/z80.c
@@ -170,6 +170,16 @@ static inline void stack_push(Z80 *z80, uint16_t value)
 }
 
 /*
+    Pop a two-byte value from the stack.
+*/
+static inline uint16_t stack_pop(Z80 *z80)
+{
+    uint16_t value = mmu_read_double(z80->mmu, z80->regfile.sp);
+    z80->regfile.sp += 2;
+    return value;
+}
+
+/*
     Read and return a byte from the given port.
 */
 static uint8_t read_port(Z80 *z80, uint8_t port)
diff --git a/src/z80_ops.inc.c b/src/z80_ops.inc.c
index 17aa15c..bebcc1d 100644
--- a/src/z80_ops.inc.c
+++ b/src/z80_ops.inc.c
@@ -225,7 +225,7 @@ static uint8_t z80_inst_ld_dd_nn(Z80 *z80, uint8_t opcode)
 static uint8_t z80_inst_push_qq(Z80 *z80, uint8_t opcode)
 {
     uint8_t pair = extract_pair(opcode);
-    stack_push(z80, pair);
+    stack_push(z80, get_pair(z80, pair));
     z80->regfile.pc++;
     return 11;
 }
@@ -234,7 +234,17 @@ static uint8_t z80_inst_push_qq(Z80 *z80, uint8_t opcode)
 
 // PUSH IY
 
-// POP qq
+/*
+    POP qq (0xC1, 0xD1, 0xE1, 0xF1):
+    Pop qq from the stack, and increment SP by two.
+*/
+static uint8_t z80_inst_pop_qq(Z80 *z80, uint8_t opcode)
+{
+    uint8_t pair = extract_pair(opcode);
+    set_pair(z80, pair, stack_pop(z80));
+    z80->regfile.pc++;
+    return 10;
+}
 
 // POP IX
 
@@ -594,7 +604,7 @@ static uint8_t z80_inst_jp_cc_nn(Z80 *z80, uint8_t opcode)
 static uint8_t z80_inst_jr_e(Z80 *z80, uint8_t opcode)
 {
     (void) opcode;
-    int8_t jump = mmu_read_byte(z80->mmu, ++z80->regfile.pc);
+    int8_t jump = mmu_read_byte(z80->mmu, z80->regfile.pc + 1);
     z80->regfile.pc += jump + 2;
     return 12;
 }
@@ -607,7 +617,7 @@ static uint8_t z80_inst_jr_e(Z80 *z80, uint8_t opcode)
 static uint8_t z80_inst_jr_cc_e(Z80 *z80, uint8_t opcode)
 {
     if (extract_cond(z80, opcode - 0x20)) {
-        int8_t jump = mmu_read_byte(z80->mmu, ++z80->regfile.pc);
+        int8_t jump = mmu_read_byte(z80->mmu, z80->regfile.pc + 1);
         z80->regfile.pc += jump + 2;
         return 12;
     } else {
diff --git a/src/z80_tables.inc.c b/src/z80_tables.inc.c
index 5425a81..1798387 100644
--- a/src/z80_tables.inc.c
+++ b/src/z80_tables.inc.c
@@ -195,7 +195,7 @@ static DispatchTable instruction_table = {
     [0xBE] = z80_inst_unimplemented,  // TODO
     [0xBF] = z80_inst_cp_r,
     [0xC0] = z80_inst_unimplemented,  // TODO
-    [0xC1] = z80_inst_unimplemented,  // TODO
+    [0xC1] = z80_inst_pop_qq,
     [0xC2] = z80_inst_jp_cc_nn,
     [0xC3] = z80_inst_jp_nn,
     [0xC4] = z80_inst_call_cc_nn,
@@ -211,7 +211,7 @@ static DispatchTable instruction_table = {
     [0xCE] = z80_inst_unimplemented,  // TODO
     [0xCF] = z80_inst_unimplemented,  // TODO
     [0xD0] = z80_inst_unimplemented,  // TODO
-    [0xD1] = z80_inst_unimplemented,  // TODO
+    [0xD1] = z80_inst_pop_qq,
     [0xD2] = z80_inst_jp_cc_nn,
     [0xD3] = z80_inst_out_n_a,
     [0xD4] = z80_inst_call_cc_nn,
@@ -227,7 +227,7 @@ static DispatchTable instruction_table = {
     [0xDE] = z80_inst_unimplemented,  // TODO
     [0xDF] = z80_inst_unimplemented,  // TODO
     [0xE0] = z80_inst_unimplemented,  // TODO
-    [0xE1] = z80_inst_unimplemented,  // TODO
+    [0xE1] = z80_inst_pop_qq,
     [0xE2] = z80_inst_jp_cc_nn,
     [0xE3] = z80_inst_unimplemented,  // TODO
     [0xE4] = z80_inst_call_cc_nn,
@@ -243,7 +243,7 @@ static DispatchTable instruction_table = {
     [0xEE] = z80_inst_unimplemented,  // TODO
     [0xEF] = z80_inst_unimplemented,  // TODO
     [0xF0] = z80_inst_unimplemented,  // TODO
-    [0xF1] = z80_inst_unimplemented,  // TODO
+    [0xF1] = z80_inst_pop_qq,
     [0xF2] = z80_inst_jp_cc_nn,
     [0xF3] = z80_inst_di,
     [0xF4] = z80_inst_call_cc_nn,