From 03066c54eb0185a0a0ebe052a77078bd832164e3 Mon Sep 17 00:00:00 2001
From: Ben Kurtovic <ben.kurtovic@gmail.com>
Date: Fri, 27 Mar 2015 16:02:54 -0400
Subject: [PATCH] Implement INC ss.

---
 src/z80.c                | 37 +++++++++++++++++++++++++++++++++++++
 src/z80_instructions.inc | 30 ++++++++++++++++++++++++++----
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/src/z80.c b/src/z80.c
index 8bcf29f..3cb2186 100644
--- a/src/z80.c
+++ b/src/z80.c
@@ -4,6 +4,11 @@
 #include "logging.h"
 #include "z80.h"
 
+#define REG_AF 0
+#define REG_BC 1
+#define REG_DE 2
+#define REG_HL 3
+
 #define FLAG_CARRY     0
 #define FLAG_SUBTRACT  1
 #define FLAG_PARITY    2
@@ -63,6 +68,38 @@ void z80_power(Z80 *z80)
 }
 
 /*
+    Get the value of a register pair.
+*/
+static inline uint16_t get_pair(Z80 *z80, uint8_t pair)
+{
+    Z80RegFile *regfile = &z80->regfile;
+
+    switch (pair) {
+        case REG_AF: return (((uint16_t) regfile->a) << 8) + regfile->f;
+        case REG_BC: return (((uint16_t) regfile->b) << 8) + regfile->c;
+        case REG_DE: return (((uint16_t) regfile->d) << 8) + regfile->e;
+        case REG_HL: return (((uint16_t) regfile->h) << 8) + regfile->l;
+        default: FATAL("Invalid call: get_pair(z80, %u)", pair)
+    }
+}
+
+/*
+    Set the value of a register pair.
+*/
+static inline void set_pair(Z80 *z80, uint8_t pair, uint16_t value)
+{
+    Z80RegFile *regfile = &z80->regfile;
+
+    switch (pair) {
+        case REG_AF: regfile->a = value >> 8; regfile->f = value; break;
+        case REG_BC: regfile->b = value >> 8; regfile->c = value; break;
+        case REG_DE: regfile->d = value >> 8; regfile->e = value; break;
+        case REG_HL: regfile->h = value >> 8; regfile->l = value; break;
+        default: FATAL("Invalid call: set_pair(z80, %u, 0x%04X)", pair, value)
+    }
+}
+
+/*
     Return whether a particular flag is set in the F register.
 */
 static inline bool get_flag(const Z80 *z80, uint8_t flag)
diff --git a/src/z80_instructions.inc b/src/z80_instructions.inc
index d980749..b9aa3cb 100644
--- a/src/z80_instructions.inc
+++ b/src/z80_instructions.inc
@@ -62,11 +62,33 @@ static uint8_t z80_inst_inc_r(Z80 *z80, uint8_t opcode)
     return 4;
 }
 
+/*
+    INC ss (0x03, 0x13, 0x23, 0x33):
+    Increment the 16-bit register encoded in the opcode.
+*/
+static uint8_t z80_inst_inc_ss(Z80 *z80, uint8_t opcode)
+{
+    if (opcode == 0x33) {
+        z80->regfile.sp++;
+    } else {
+        uint8_t pair;
+        switch(opcode) {
+            case 0x03: pair = REG_BC; break;
+            case 0x13: pair = REG_DE; break;
+            case 0x23: pair = REG_HL; break;
+        }
+        set_pair(z80, pair, get_pair(z80, pair) + 1);
+    }
+
+    z80->regfile.pc++;
+    return 6;
+}
+
 static uint8_t (*instruction_lookup_table[256])(Z80*, uint8_t) = {
     /* 0x00 */ z80_inst_nop,
     /* 0x01 */ z80_inst_unimplemented,  // TODO
     /* 0x02 */ z80_inst_unimplemented,  // TODO
-    /* 0x03 */ z80_inst_unimplemented,  // TODO
+    /* 0x03 */ z80_inst_inc_ss,
     /* 0x04 */ z80_inst_inc_r,
     /* 0x05 */ z80_inst_unimplemented,  // TODO
     /* 0x06 */ z80_inst_unimplemented,  // TODO
@@ -82,7 +104,7 @@ static uint8_t (*instruction_lookup_table[256])(Z80*, uint8_t) = {
     /* 0x10 */ z80_inst_unimplemented,  // TODO
     /* 0x11 */ z80_inst_unimplemented,  // TODO
     /* 0x12 */ z80_inst_unimplemented,  // TODO
-    /* 0x13 */ z80_inst_unimplemented,  // TODO
+    /* 0x13 */ z80_inst_inc_ss,
     /* 0x14 */ z80_inst_inc_r,
     /* 0x15 */ z80_inst_unimplemented,  // TODO
     /* 0x16 */ z80_inst_unimplemented,  // TODO
@@ -98,7 +120,7 @@ static uint8_t (*instruction_lookup_table[256])(Z80*, uint8_t) = {
     /* 0x20 */ z80_inst_unimplemented,  // TODO
     /* 0x21 */ z80_inst_unimplemented,  // TODO
     /* 0x22 */ z80_inst_unimplemented,  // TODO
-    /* 0x23 */ z80_inst_unimplemented,  // TODO
+    /* 0x23 */ z80_inst_inc_ss,
     /* 0x24 */ z80_inst_inc_r,
     /* 0x25 */ z80_inst_unimplemented,  // TODO
     /* 0x26 */ z80_inst_unimplemented,  // TODO
@@ -114,7 +136,7 @@ static uint8_t (*instruction_lookup_table[256])(Z80*, uint8_t) = {
     /* 0x30 */ z80_inst_unimplemented,  // TODO
     /* 0x31 */ z80_inst_unimplemented,  // TODO
     /* 0x32 */ z80_inst_unimplemented,  // TODO
-    /* 0x33 */ z80_inst_unimplemented,  // TODO
+    /* 0x33 */ z80_inst_inc_ss,
     /* 0x34 */ z80_inst_unimplemented,  // TODO
     /* 0x35 */ z80_inst_unimplemented,  // TODO
     /* 0x36 */ z80_inst_unimplemented,  // TODO