From af8475caf71cc8c85a1932e4752161ba34519294 Mon Sep 17 00:00:00 2001
From: Zoe Roux <zoe.roux@zoriya.dev>
Date: Tue, 11 Jul 2023 15:57:12 +0900
Subject: [PATCH] Make a5 and a6 work

---
 src/instructions.c             |  8 ++++----
 src/instructions.h             |  1 +
 src/instructions/arithmetics.c | 25 ++++++++++++++++++++++++-
 3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/instructions.c b/src/instructions.c
index ae6b976..d85766d 100644
--- a/src/instructions.c
+++ b/src/instructions.c
@@ -343,7 +343,7 @@ const instruction_t extended[][8] = {
 		{.opcode = 0x04, .extended = -2, .name = "shl %s, 1", .mode = {R_M8, END}, .exec = &shl},
 		{.opcode = 0x05, .extended = -2, .name = "shr %s, 1", .mode = {R_M8, END}, .exec = NULL},
 		/**/{.opcode = 0x06, .extended = -2, .name = "invalid", .mode = {END}, .exec = NULL},
-		{.opcode = 0x07, .extended = -2, .name = "sar %s, 1", .mode = {R_M8, END}, .exec = NULL},
+		{.opcode = 0x07, .extended = -2, .name = "sar %s, 1", .mode = {R_M8, END}, .exec = &sar},
 	},
 	// 0xd1 extended
 	{
@@ -354,7 +354,7 @@ const instruction_t extended[][8] = {
 		{.opcode = 0x04, .extended = -2, .name = "shl %s, 1", .mode = {R_M16, END}, .exec = &shl},
 		{.opcode = 0x05, .extended = -2, .name = "shr %s, 1", .mode = {R_M16, END}, .exec = NULL},
 		/**/{.opcode = 0x06, .extended = -2, .name = "invalid", .mode = {END}, .exec = NULL},
-		{.opcode = 0x07, .extended = -2, .name = "sar %s, 1", .mode = {R_M16, END}, .exec = NULL},
+		{.opcode = 0x07, .extended = -2, .name = "sar %s, 1", .mode = {R_M16, END}, .exec = &sar},
 	},
 	// 0xd2 extended
 	{
@@ -365,7 +365,7 @@ const instruction_t extended[][8] = {
 		{.opcode = 0x04, .extended = -2, .name = "shl %s, cl", .mode = {R_M8, END}, .exec = &shl},
 		{.opcode = 0x05, .extended = -2, .name = "shr %s, cl", .mode = {R_M8, END}, .exec = NULL},
 		/**/{.opcode = 0x06, .extended = -2, .name = "invalid", .mode = {END}, .exec = NULL},
-		{.opcode = 0x07, .extended = -2, .name = "sar %s, cl", .mode = {R_M8, END}, .exec = NULL},
+		{.opcode = 0x07, .extended = -2, .name = "sar %s, cl", .mode = {R_M8, END}, .exec = &sar},
 	},
 	// 0xd3 extended
 	{
@@ -376,7 +376,7 @@ const instruction_t extended[][8] = {
 		{.opcode = 0x04, .extended = -2, .name = "shl %s, cl", .mode = {R_M16, END}, .exec = &shl},
 		{.opcode = 0x05, .extended = -2, .name = "shr %s, cl", .mode = {R_M16, END}, .exec = NULL},
 		/**/{.opcode = 0x06, .extended = -2, .name = "invalid", .mode = {END}, .exec = NULL},
-		{.opcode = 0x07, .extended = -2, .name = "sar %s, cl", .mode = {R_M16, END}, .exec = NULL},
+		{.opcode = 0x07, .extended = -2, .name = "sar %s, cl", .mode = {R_M16, END}, .exec = &sar},
 	},
 };
 
diff --git a/src/instructions.h b/src/instructions.h
index 8f7a353..2d765fd 100644
--- a/src/instructions.h
+++ b/src/instructions.h
@@ -44,4 +44,5 @@ void cbw(const instruction_t *self, state_t *state);
 void cwd(const instruction_t *self, state_t *state);
 void neg(const instruction_t *self, state_t *state);
 void shl(const instruction_t *self, state_t *state);
+void sar(const instruction_t *self, state_t *state);
 void xchg(const instruction_t *self, state_t *state);
diff --git a/src/instructions/arithmetics.c b/src/instructions/arithmetics.c
index 02ab7a2..6ff3337 100644
--- a/src/instructions/arithmetics.c
+++ b/src/instructions/arithmetics.c
@@ -201,11 +201,34 @@ void shl(const instruction_t *self, state_t *state)
 
 	write_op(to, new);
 
-	state->cf = value >> (8 - shft);
+	state->of = new != read_op(to);
+	state->cf = value >> (8 - shft) & 1;
 	state->sf = new & (is_operand_wide(self, 0) ? 0x8000 : 0x80);
 	state->zf = new == 0;
 }
 
+void sar(const instruction_t *self, state_t *state)
+{
+	operand_t to = get_operand(self, 0, state);
+	unsigned value = read_op(to);
+	uint8_t opgrp =state->binary[state->pc];
+	unsigned shft = (opgrp == 0xd0 || opgrp == 0xd1) ? 1 : state->cl;
+
+	unsigned signMask = (is_operand_wide(self, 0) ? 0x8000 : 0x80);
+
+	unsigned new = value >> shft;
+	if (value & signMask)
+		new |= signMask;
+	else
+		new &= ~signMask;
+
+	write_op(to, new);
+
+	state->cf = (value >> (shft - 1)) & 1;
+	state->sf = value & signMask;
+	state->zf = new == 0;
+}
+
 void xchg(const instruction_t *self, state_t *state)
 {
 	operand_t from = get_operand(self, 0, state);