From c10f2153ffa3e8dd0d53fa9c106caa23669ee0d5 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Thu, 17 Jun 2021 23:43:31 -0400
Subject: [PATCH] unused code to guess what sort of media a disk image is. The
 general idea would be drag-n-drop a file (or double-click from the disk image
 window, etc) and auto-place it in the right place.

---
 Ample/Media.m | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)

diff --git a/Ample/Media.m b/Ample/Media.m
index 612a562..ff8d458 100644
--- a/Ample/Media.m
+++ b/Ample/Media.m
@@ -59,3 +59,144 @@ BOOL MediaEqual(const Media *lhs, const Media *rhs) {
     return YES;
 #undef _
 }
+
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+enum {
+    MediaType_5_25,
+    MediaType_3_5,
+    MediaType_HardDisk,
+    MediaType_CD,
+    MediaType_Cassette,
+};
+
+#define _x2(a,b) (a | (b << 8))
+#define _x3(a,b,c) (a | (b << 8) | (c << 16))
+#define _x4(a,b,c, d) (a | (b << 8) | (c << 16) | (d << 24))
+static unsigned hash(const char *cp) {
+    unsigned rv = 0;
+    int i, shift;
+    if (!cp) return 0;
+    for (i = 0, shift = 0; i < 4; ++i, shift += 8) {
+        unsigned c = cp[0];
+        if (!c) break;
+        c = tolower(c);
+        rv |= (c << shift);
+    }
+    if (i > 4) return 0;
+    return rv;
+}
+
+const char *extname(const char *path) {
+    
+    const char *rv = NULL;
+    if (!path) return path;
+    for(unsigned i = 0; ; ++i) {
+        unsigned c = path[i];
+        if (c == 0) break;
+        if (c == '/') rv = NULL;
+        if (c == '.') rv = path + i + 1;
+    }
+    if (rv && !*rv) rv = NULL;
+    return rv;
+}
+
+int ClassifyMediaFile(NSString *file) {
+    
+    struct stat st;
+    ssize_t size;
+    unsigned char buffer[128];
+    int fd;
+    const char *path = [file fileSystemRepresentation];
+    const char *ext = extname(path);
+    unsigned ext_hash = hash(ext);
+
+    memset(&st, 0, sizeof(st));
+    memset(buffer, 0, sizeof(buffer));
+
+    fd = open(path, O_RDONLY);
+    if (fd < 0) return -1;
+    fstat(fd, &st);
+    
+    size = read(fd, buffer, sizeof(buffer));
+    close(fd);
+    if (size <= 0) return -1;
+
+    // 13 sector support ? not on an event 512 block boundary.
+    // = 116480 bytes.
+    
+    /* woz 1/2 ? */
+    if (!memcmp(buffer, "WOZ1\xff\x0a\x0d\x0a", 8) || !memcmp(buffer, "WOZ2\xff\x0a\x0d\x0a", 8)) {
+
+        if (!memcmp(buffer + 12, "INFO", 4)) {
+            unsigned type = buffer[21]; // 1 = 5.25, 2 = 3.5
+            if (type == 1) return MediaType_5_25;
+            if (type == 2) return MediaType_3_5;
+        }
+        return -1;
+    }
+    
+    /* 2mg? */
+    if (!memcmp(buffer, "2IMG", 4)) {
+        int format = OSReadLittleInt32(buffer, 0x0c); // 0 - dos order, 1 = prodos order, 2 = nib data
+        int blocks = OSReadLittleInt32(buffer, 0x14); // prodos only.
+        //int bytes = OSReadLittleInt32(buffer, 0x1c);
+        
+        if (format == 2 || format == 0) return MediaType_5_25; // nib and dos order
+        if (blocks == 280) return MediaType_5_25;
+        if (blocks == 800 || blocks == 1600 || blocks == 1440 || blocks == 2880) return MediaType_3_5;
+        if (blocks > 2880) return MediaType_HardDisk; //
+        return -1;
+    }
+    
+    /* chd? */
+    if (!memcmp(buffer, "MComprHD", 8)) {
+        static int offsets[] = { 0, 0, 0, 28, 28, 32}; // offset for logival bytes.
+        int version = OSReadBigInt32(buffer, 12);
+
+        if (version >= 3 && version <= 5) {
+            long bytes = OSReadBigInt64(buffer, offsets[version]);
+            long blocks = bytes >> 9;
+            if ((bytes & 511) == 0) {
+                if (blocks == 800 || blocks == 1600 || blocks == 1440 || blocks == 2880) return MediaType_3_5;
+                if (blocks == 280) return MediaType_5_25;
+                if (blocks > 2880) return MediaType_HardDisk; // iso?
+            }
+        }
+        return -1;
+    }
+    
+    
+    /* dc 4.2? magic is pretty weak. */
+    if (buffer[0x52] == 0x01 && buffer[0x53] == 0x00 && buffer[0] >= 1 && buffer[0] <= 0x3f) {
+        int dsize = OSReadBigInt32(buffer, 0x40);
+        int tsize = OSReadBigInt32(buffer, 0x44);
+        if (dsize + tsize + 0x54 == st.st_size && (size & 511) == 0) {
+            int blocks = dsize >>= 9;
+            if (blocks == 800 || blocks == 1600 || blocks == 1440 || blocks == 2880) return MediaType_3_5;
+        }
+    }
+
+    switch(ext_hash) {
+        case _x3('n', 'i', 'b'): return MediaType_5_25;
+        case _x3('w', 'a', 'v'): return MediaType_Cassette;
+        case _x3('i', 's', 'o'):
+        case _x3('c', 'u', 'e'):
+        case _x3('c', 'd', 'r'):
+            return MediaType_CD;
+
+        // po, do, hdv, dsk - based on size
+        case _x2('d', 'o'):
+        case _x3('d', 's', 'k'):
+        case _x2('p', 'o'):
+        case _x3('h', 'd', 'v'): // usually 3.5 or hard drive
+            if (st.st_size <= 143360) return MediaType_5_25;
+            if (st.st_size <= 1474560) return MediaType_3_5;
+            return MediaType_HardDisk;
+            return MediaType_HardDisk;
+    }
+
+    return -1;
+}