[Decompilation] [th01] REIIDEN.CFG loading and saving

That's where the backwards `goto` for .CFG file error handling
originated!

Part of P0090, funded by Yanga.

th01/formats/cfg.hpp

@@ -0,0 +1,21 @@
+#define CFG_FN "reiiden.cfg"
+#define CFG_ID "REIIDEN"
+
+struct cfg_options_t {
+	int8_t rank;
+	int8_t bgm_mode;
+	int8_t bombs;
+	int8_t lives_extra;	// Add 2 for the actual number of lives
+};
+
+#define CFG_RANK_DEFAULT (RANK_NORMAL)
+#define CFG_BGM_MODE_DEFAULT (true)
+#define CFG_BOMBS_DEFAULT (1)
+#define CFG_LIVES_EXTRA_DEFAULT (2)
+
+#define CFG_LIVES_EXTRA_MAX (4)
+
+struct cfg_t {
+	char id[sizeof(CFG_ID) - 1];
+	cfg_options_t opts;
+};

th01/formats/cfg.inc

@@ -0,0 +1,13 @@
+cfg_options_t	struc
+	O_rank	db ?
+	O_bgm_mode	db ?
+	O_bombs	db ?
+	O_lives_extra	db ?
+cfg_options_t	ends
+
+CFG_RANK_DEFAULT = RANK_NORMAL
+CFG_BGM_MODE_DEFAULT = 1
+CFG_BOMBS_DEFAULT = 1
+CFG_LIVES_EXTRA_DEFAULT = 2
+
+CFG_LIVES_EXTRA_MAX = 4

th01/formats/cfg[data].asm

@@ -0,0 +1,6 @@
+public _CFG_FN, _CFG_ID, _FOPEN_RB, _FOPEN_WB
+_CFG_FN  	db 'reiiden.cfg',0
+_FOPEN_RB	db 'rb',0
+_REIIDEN label byte
+_CFG_ID  	db 'REIIDEN',0
+_FOPEN_WB	db 'wb',0

th01/op_01.cpp

@@ -3,9 +3,14 @@
  * Code segment #1 of TH01's OP.EXE
  */
 
+#pragma option -Z
+
 extern "C" {
+#include <stdio.h>
 #include "ReC98.h"
+#include "th01/ranks.h"
 #include "th01/hardware/graph.h"
+#include "th01/formats/cfg.hpp"
 
 // Unused. The only thing on the main menu with this color is the "1996 ZUN"
 // text at the bottom... probably part of an effect that we never got to see.
@@ -36,4 +41,60 @@ void snap_col_4(void)
 	graph_accesspage_func(0);
 }
 
+/// REIIDEN.CFG loading and saving
+/// ------------------------------
+extern cfg_options_t opts;
+// These will be removed once the strings can be defined here
+#undef CFG_FN
+#undef CFG_ID
+extern const char CFG_FN[], CFG_ID[], FOPEN_RB[], FOPEN_WB[];
+
+void cfg_load(void)
+{
+	cfg_t cfg_in;
+	bool read_failure = false;
+	FILE* fp;
+
+	if(( fp = fopen(CFG_FN, FOPEN_RB) ) == NULL) {
+use_defaults:
+		read_failure = true;
+	}
+	if(!read_failure) {
+		fread(&cfg_in, 1, sizeof(cfg_in), fp);
+		if(memcmp(cfg_in.id, CFG_ID, sizeof(cfg_in.id))) {
+			fclose(fp);
+			goto use_defaults;
+		}
+		opts.rank = cfg_in.opts.rank;
+		opts.bgm_mode = cfg_in.opts.bgm_mode;
+		opts.bombs = cfg_in.opts.bombs;
+		opts.lives_extra = cfg_in.opts.lives_extra;
+		fclose(fp);
+	} else {
+		opts.rank = CFG_RANK_DEFAULT;
+		opts.bgm_mode = CFG_BGM_MODE_DEFAULT;
+		opts.bombs = CFG_BOMBS_DEFAULT;
+		opts.lives_extra = CFG_LIVES_EXTRA_DEFAULT;
+	}
+}
+
+void cfg_save(void)
+{
+	bool write_failure = false;
+	FILE* fp;
+
+	if(( fp = fopen(CFG_FN, FOPEN_WB) ) == NULL) {
+		write_failure = true;
+	}
+	if(!write_failure) {
+		fputs(CFG_ID, fp);
+		fputc(opts.rank, fp);
+		fputc(opts.bgm_mode, fp);
+		fputc(opts.bombs, fp);
+		fputc(opts.lives_extra, fp);
+		fclose(fp);
+	}
+}
+/// ------------------------------
+
 }