Initial commit

backends/platform/atari/native_features.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// Taken from mintlib (https://github.com/freemint/mintlib)
+// (c) Thorsten Otto
+
+#include <mint/osbind.h>
+#include <stdint.h>
+
+#define NATFEAT_ID   0x7300
+#define NATFEAT_CALL 0x7301
+
+#define ASM_NATFEAT3(opcode) "\t.word " #opcode "\n"
+#define ASM_NATFEAT2(opcode) ASM_NATFEAT3(opcode)
+#define ASM_NATFEAT(n) ASM_NATFEAT2(n)
+
+static unsigned short const nf_id_opcodes[] = { NATFEAT_ID, 0x4e75 };
+static unsigned short const nf_call_opcodes[] = { NATFEAT_CALL, 0x4e75 };
+
+#define _nf_get_id(feature_name) ((long (__CDECL *)(const char *))nf_id_opcodes)(feature_name)
+#define _nf_call(id, ...) ((long (__CDECL *)(long, ...))nf_call_opcodes)(id, __VA_ARGS__)
+
+/*
+ * on ColdFire, the NATFEAT_ID opcode is actually
+ * "mvs.b d0,d1",
+ * which means the following code will NOT detect
+ * the presence of an emulator (should there ever
+ * be an emulator capable of emulating a ColdFire processor).
+ * Luckily, executing the code on a CF processor is still
+ * harmless since all it does is clobber D1.
+ */
+static long _nf_detect_tos(void) {
+	register long ret __asm__ ("d0");
+	register const char *nf_version __asm__("a1") = "NF_VERSION";
+
+	__asm__ volatile(
+	"\tmove.l	%1,-(%%sp)\n"
+	"\tmoveq	#0,%%d0\n"			/* assume no NatFeats available */
+	"\tmove.l	%%d0,-(%%sp)\n"
+	"\tlea		(1f:w,%%pc),%%a1\n"
+	"\tmove.l	(0x0010).w,%%a0\n"	/* illegal instruction vector */
+	"\tmove.l	%%a1,(0x0010).w\n"
+	"\tmove.l	%%sp,%%a1\n"		/* save the ssp */
+
+	"\tnop\n"						/* flush pipelines (for 68040+) */
+
+	ASM_NATFEAT(NATFEAT_ID)			/* Jump to NATFEAT_ID */
+	"\ttst.l	%%d0\n"
+	"\tbeq.s	1f\n"
+	"\tmoveq	#1,%%d0\n"			/* NatFeats detected */
+	"\tmove.l	%%d0,(%%sp)\n"
+
+"1:\n"
+	"\tmove.l	%%a1,%%sp\n"
+	"\tmove.l	%%a0,(0x0010).w\n"
+	"\tmove.l	(%%sp)+,%%d0\n"
+	"\taddq.l	#4,%%sp\n"			/* pop nf_version argument */
+
+	"\tnop\n"						/* flush pipelines (for 68040+) */
+	: "=g"(ret)  /* outputs */
+	: "g"(nf_version)		/* inputs  */
+	: __CLOBBER_RETURN("d0") "a0", "d1", "cc" AND_MEMORY
+	);
+	return ret;
+}
+
+long nf_stderr_id;
+
+void nf_init(void) {
+	long ret = Supexec(_nf_detect_tos);
+	if (ret == 1)
+		nf_stderr_id = _nf_get_id("NF_STDERR");
+}
+
+void nf_print(const char* msg) {
+	if (nf_stderr_id)
+		_nf_call(nf_stderr_id | 0, (uint32_t)msg);
+}