From e2f4e398c33f30f9b03448fb6687b7e06a65f21f Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Sun, 22 Mar 2020 21:28:09 +0000
Subject: Added load/save and some extra instructions.

---
 doc/instruction.txt |  20 ++++++
 src/Makefile        |   1 +
 src/czx81.c         | 172 +++++++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 186 insertions(+), 7 deletions(-)

diff --git a/doc/instruction.txt b/doc/instruction.txt
index a399cd7..530dab9 100644
--- a/doc/instruction.txt
+++ b/doc/instruction.txt
@@ -44,6 +44,9 @@ KEYBOARD
     BACKSPACE   - Emulate the RUBOUT key (shift 0)
     DELETE      - Emulate the RUBOUT key (shift 0)
 
+    When emulating the keyboard the key is held down for a default of one frame.
+    This can be altered in the runtime menu.
+
 
 LOADING AND SAVING
 ------------------
@@ -58,6 +61,23 @@ LOADING AND SAVING
     be enabled.  See the CONFIGURATION FILE section.
 
 
+RUNTIME MENU
+------------
+
+    When you press ESCAPE the runtime menu is displayed and offers the following
+    options:
+
+    F1          - Toggle tracing on and off.  When on tracing will display the
+                  disassembly at the PC and the state of the Z80 registers.
+
+    F2          - Alter the number of frames the key is held down following a
+                  keypress.  The default of 1 works OK for BASIC.
+
+    F3          - Reset the ZX81.
+
+    F4          - Quit the emulator.
+
+
 CONFIGURATION FILE
 ------------------
 
diff --git a/src/Makefile b/src/Makefile
index 9fc766e..e1aa066 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -17,6 +17,7 @@
 TARGET=czx81
 
 # This library may need to be set to one of these:
+#	curses
 #	cursesw
 #	ncursesw
 CURSES=-lncurses
diff --git a/src/czx81.c b/src/czx81.c
index 27bfe5b..55bae6a 100644
--- a/src/czx81.c
+++ b/src/czx81.c
@@ -111,6 +111,9 @@ static int		current_key = -1;
 
 static int		trace = FALSE;
 
+static char		snappath[4096] = ".";
+static int		allow_save = FALSE;
+
 static struct
 {
     int		key;		/* The curses keycode */
@@ -291,6 +294,101 @@ static void RenderScreen(void)
 }
 
 
+static FILE *OpenTapeFile(Z80Word addr, const char *mode)
+{
+    static const char zx_chars[] = "\"#$:?()><=+-*/;,."
+				   "0123456789"
+				   "abcdefghijklmnopqrstuvwxyz";
+    char full_fn[4096];
+    char fn[4096];
+    int f;
+    int done;
+
+    done = FALSE;
+    f = 0;
+
+    while(!done)
+    {
+    	int ch;
+
+	ch = mem[addr++];
+
+	if (ch & 0x80)
+	{
+	    done = TRUE;
+	    ch &= 0x7f;
+	}
+
+	if (ch >= 11 && ch <=63)
+	{
+	    fn[f++] = zx_chars[ch - 11];
+	}
+    }
+
+    fn[f] = 0;
+
+    sprintf(full_fn, "%s/%s", snappath, fn);
+
+    return fopen(full_fn, mode);
+}
+
+
+static void ReadConfig(void)
+{
+    char fn[4096] = {0};
+    char *env;
+    FILE *fp;
+
+    if ((env = getenv("HOME")))
+    {
+    	strcpy(fn, env);
+	strcat(fn, "/");
+    }
+
+    strcat(fn, ".czx81rc");
+
+    if ((fp = fopen(fn, "r")))
+    {
+    	char s[4096];
+
+	while(fgets(s, sizeof s, fp))
+	{
+	    size_t l;
+	    char *tok1 = NULL;
+	    char *tok2 = NULL;
+
+	    l = strlen(s);
+
+	    while(l && s[l - 1] == '\n')
+	    {
+	    	s[--l] = 0;
+	    }
+
+	    tok1 = strtok(s, " \t");
+
+	    if (tok1)
+	    {
+	    	tok2 = strtok(NULL, " \t");
+	    }
+
+	    if (strcmp(tok1, "snappath") == 0)
+	    {
+	    	if (tok2)
+		{
+		    strcpy(snappath, tok2);
+		}
+	    }
+	    else if (strcmp(tok1, "allowsave") == 0)
+	    {
+	    	allow_save = TRUE;
+	    }
+	}
+
+    	fclose(fp);
+    }
+}
+
+
 /* -------------------------------------------------- ZX81 CODE
 */
 static void RomPatch(const Z80Byte patch[], Z80Word addr)
@@ -552,14 +650,34 @@ static void PressKey(int key)
 
 static int EDCallback(Z80 *z80, Z80Val data)
 {
-    Z80Word pause;
-
     switch((Z80Byte)data)
     {
     	case ED_SAVE:
-	    if (z80->DE.w < 0x8000)
+	    if (allow_save && z80->DE.w < 0x8000)
 	    {
-	    	/* TODO: Save */
+		FILE *fp;
+
+		fp = OpenTapeFile(z80->HL.w, "wb");
+
+		if (fp)
+		{
+		    int f;
+		    int end;
+
+		    f = 0x4009;
+		    end = PEEKW(E_LINE);
+
+		    while(f <= end)
+		    {
+		    	fputc(mem[f++], fp);
+		    }
+
+		    fclose(fp);
+		}
+		else
+		{
+		    sprintf(message, "Failed to open file");
+		}
 	    }
 
 	    break;
@@ -567,7 +685,28 @@ static int EDCallback(Z80 *z80, Z80Val data)
 	case ED_LOAD:
 	    if (z80->DE.w < 0x8000)
 	    {
-	    	/* TODO: Load */
+		FILE *fp;
+
+		fp = OpenTapeFile(z80->DE.w, "rb");
+
+		if (fp)
+		{
+		    int c;
+		    Z80Byte *a;
+
+		    a = mem + 0x4009;
+
+		    while((c = getc(fp)) != EOF)
+		    {
+		    	*a++ = c;
+		    }
+
+		    fclose(fp);
+		}
+		else
+		{
+		    sprintf(message, "Failed to open file");
+		}
 	    }
 
 	    mem[CDFLAG] = 0xc0;
@@ -584,20 +723,37 @@ static int EDCallback(Z80 *z80, Z80Val data)
 	    break;
 
 	case ED_PAUSE:
+	{
+	    Z80Word pause;
+	    struct timespec start;
+
 	    waitkey = TRUE;
 
 	    pause = z80->BC.w;
 
 	    while(pause-- && !(mem[CDFLAG]&1))
 	    {
+		struct timespec end;
+		struct timespec pause = {0};
+
 	    	ClearScreen();
 		PressKey(getch());
 		CheckTimers(z80, FRAME_TSTATES);
 		RenderScreen();
+
+		clock_gettime(CLOCK_MONOTONIC, &end);
+		start = end;
+		pause.tv_nsec = 20000000 - TimeDiff(&start, &end);
+
+		if (pause.tv_nsec > 0 && FRAME_TSTATES != FAST_TSTATES)
+		{
+		    nanosleep(&pause, NULL);
+		}
 	    }
 
 	    waitkey = FALSE;
 	    break;
+	}
     }
 
     return TRUE;
@@ -840,6 +996,8 @@ int main(void)
 
     setlocale(LC_ALL, "");
 
+    ReadConfig();
+
     z80 = Z80Init(ZX81ReadMem,
     		  ZX81WriteMem,
 		  ZX81ReadPort,
@@ -862,14 +1020,14 @@ int main(void)
 
     clock_gettime(CLOCK_MONOTONIC, &start);
 
-    ClearScreen();
-
     while(!quit)
     {
 	struct timespec end;
 	struct timespec pause = {0};
 	int ch;
 
+	ClearScreen();
+
 	Z80Exec(z80);
 
 	ch = getch();
-- 
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