Added ZX81 output driver

1 files changed, 268 insertions, 0 deletions

diff --git a/src/zx81out.c b/src/zx81out.c
new file mode 100644
index 0000000..fe4d83c
--- /dev/null
+++ b/src/zx81out.c
@@ -0,0 +1,268 @@
+/*
+
+    casm - Simple, portable assembler
+
+    Copyright (C) 2003-2015  Ian Cowburn (ianc@noddybox.demon.co.uk)
+
+    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/>.
+
+    -------------------------------------------------------------------------
+
+    ZX81 tape output handler.
+
+*/
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "global.h"
+#include "codepage.h"
+#include "zx81out.h"
+
+
+/* ---------------------------------------- MACROS & TYPES
+*/
+
+enum option_t
+{
+    OPT_MARGIN,
+    OPT_AUTORUN,
+    OPT_DFILE_COLLAPSED
+};
+
+static const ValueTable option_set[] =
+{
+    {"zx81-margin",             OPT_MARGIN},
+    {"zx81-autorun",            OPT_AUTORUN},
+    {"zx81-collapse-dfile",     OPT_DFILE_COLLAPSED},
+    {NULL}
+};
+
+typedef enum
+{
+    PAL = 55,
+    NTSC = 31
+} TVFormat;
+
+static ValueTable       format_table[] =
+{
+    {"pal",             PAL},
+    {"NTSC",            NTSC},
+    {NULL}
+};
+
+static TVFormat         tv_format = PAL;
+static int              run = TRUE;
+static int              collapse_dfile = FALSE;
+
+/* ---------------------------------------- PRIVATE FUNCTIONS
+*/
+
+static int PokeB(Byte *mem, int addr, Byte b)
+{
+    mem[addr++] = b;
+    return (addr % 0x10000);
+}
+
+
+static int PokeW(Byte *mem, int addr, int w)
+{
+    addr = PokeB(mem, addr, w & 0xff);
+    return PokeB(mem, addr, (w & 0xff00) >> 8);
+}
+
+
+/* ---------------------------------------- INTERFACES
+*/
+const ValueTable *ZX81OutputOptions(void)
+{
+    return option_set;
+}
+
+CommandStatus ZX81OutputSetOption(int opt, int argc, char *argv[],
+                                     int quoted[],
+                                     char *err, size_t errsize)
+{
+    const ValueTable *val;
+
+    CMD_ARGC_CHECK(1);
+
+    switch(opt)
+    {
+        case OPT_MARGIN:
+            CMD_TABLE(argv[0], format_table, val);
+            tv_format = val->value;
+            break;
+
+        case OPT_AUTORUN:
+            run = ParseTrueFalse(argv[0], TRUE);
+            break;
+
+        case OPT_DFILE_COLLAPSED:
+            collapse_dfile = ParseTrueFalse(argv[0], TRUE);
+            break;
+
+        default:
+            break;
+    }
+
+    return CMD_OK;
+}
+
+int ZX81Output(const char *filename, const char *filename_bank,
+              MemoryBank **bank, int count, char *error, size_t error_size)
+{
+    static const int line[] =
+    {
+        0, 10, 14, 0, 0xf9, 0xd4, 0x1d, 0x22, 0x21, 0x1d,
+        0x20, 0x7e, 0x8f, 0x01, 0x04, 0x00, 0x00, 0x76, -1
+    };
+
+    FILE *fp = fopen(filename, "wb");
+    Byte *mem;
+    int min;
+    int max;
+    int len;
+    int next;
+    int dfile;
+    int vars;
+    int addr;
+    int f;
+
+    mem = bank[0]->memory;
+    min = bank[0]->min_address_used;
+    max = bank[0]->max_address_used;
+
+    len = max - min + 1;
+
+    if (min != 16514)
+    {
+        snprintf(error, error_size, "Code must start at 16514 to work with the "
+                                        "ZX81 output driver.");
+        return FALSE;
+    }
+
+    if (!fp)
+    {
+        snprintf(error, error_size, "Failed to create %s", filename);
+        return FALSE;
+    }
+
+    /* Create the system variables and BASIC program around the supplied code.
+       BASIC is done first to calculate various system variables.
+    */
+    addr = 16509;
+
+    /* Program line with REM statement
+    */
+    addr = PokeW(mem, addr, 0x0000);            /* Line number  */
+    addr = PokeW(mem, addr, len + 2);           /* Line length  */
+    addr = PokeB(mem, addr, 0xea);              /* REM token    */
+
+    addr += len;                                /* Skip code    */
+
+    addr = PokeB(mem, addr, 0x76);              /* NL token     */
+
+    /* Program line to launch the code
+    */
+    next = addr;
+
+    f = 0;
+    while (line[f] != -1)
+    {
+    	addr = PokeB(mem, addr, line[f++]);
+    }
+
+    /* Display file
+    */
+    dfile = addr;
+
+    if (collapse_dfile)
+    {
+        for(f = 0; f < 25; f++)
+        {
+            addr = PokeB(mem, addr, 0x76);
+        }
+    }
+    else
+    {
+        addr = PokeB(mem, addr, 0x76);
+
+        for(f = 0; f < 24; f++)
+        {
+            int n;
+
+            for(n = 0; n < 32; n++)
+            {
+                addr = PokeB(mem, addr, 0);
+            }
+
+            addr = PokeB(mem, addr, 0x76);
+        }
+    }
+
+    /* Vars
+    */
+    vars = addr;
+    addr = PokeB(mem, addr, 0x80);
+
+    /* System variables
+    */
+    addr = 0x4009;
+
+    addr = PokeB(mem, addr, 0);                 /* VERSN        */
+    addr = PokeW(mem, addr, 0);                 /* E_PPC        */
+    addr = PokeW(mem, addr, dfile);             /* D_FILE       */
+    addr = PokeW(mem, addr, dfile + 1);         /* DF_CC        */
+    addr = PokeW(mem, addr, vars);              /* VARS         */
+    addr = PokeW(mem, addr, 0);                 /* DEST         */
+    addr = PokeW(mem, addr, vars + 1);          /* E_LINE       */
+    addr = PokeW(mem, addr, vars - 1);          /* CH_ADD       */
+    addr = PokeW(mem, addr, 0);                 /* X_PTR        */
+    addr = PokeW(mem, addr, vars + 5);          /* STKBOT       */
+    addr = PokeW(mem, addr, vars + 5);          /* STKEND       */
+    addr = PokeB(mem, addr, 0);                 /* BREG         */
+    addr = PokeW(mem, addr, 16477);             /* MEM          */
+    addr = PokeB(mem, addr, 0);                 /* unused       */
+    addr = PokeB(mem, addr, 2);                 /* DF_SZ        */
+    addr = PokeW(mem, addr, 2);                 /* S_TOP        */
+    addr = PokeW(mem, addr, 0xffff);            /* LAST_K       */
+    addr = PokeB(mem, addr, 0xff);              /* LAST_K       */
+    addr = PokeB(mem, addr, tv_format);         /* MARGIN       */
+    addr = PokeW(mem, addr, run ? next : dfile);/* NXTLIN       */
+    addr = PokeW(mem, addr, 0);                 /* OLDPPC       */
+    addr = PokeB(mem, addr, 0);                 /* FLAGX        */
+    addr = PokeW(mem, addr, 0);                 /* STRLEN       */
+    addr = PokeW(mem, addr, 0xc8d);             /* T_ADDR       */
+    addr = PokeW(mem, addr, 0);                 /* SEED         */
+    addr = PokeW(mem, addr, 0x0ffff);           /* FRAMES       */
+    addr = PokeW(mem, addr, 0);                 /* COORDS       */
+    addr = PokeB(mem, addr, 0xbc);              /* PR_CC        */
+    addr = PokeB(mem, addr, 33);                /* S_POSN       */
+    addr = PokeB(mem, addr, 24);                /* S_POSN       */
+    addr = PokeW(mem, addr, 0x40);              /* CDFLAG       */
+
+    /* Write the constructed P file
+    */
+    fwrite(mem + 0x4009, vars - 0x4009 + 1, 1, fp);
+
+    fclose(fp);
+
+    return TRUE;
+}
+
+
+/*
+vim: ai sw=4 ts=8 expandtab
+*/