[WIP] XRacer - a racing gamexracer

Plan:
-----

A simple racing game like Pole Position or Enduro.

Status:
-------
 - Currently generates a random road and scrolls through it
 - Random road generation (curves and hills)
 - Supports loading of maps from a file ("/output.xrm")
 - Sample map at http://a.pomf.se/ynhlwq.xrm

Todo:
-----
 - Convert to fixed-point math in all places (only one place left!)
 - Improve/fix track looping
 - Improve random road generation to start and end at the same height
 - Finish sprite code
 - Make sprites
 - Game-ify!

What's new:
-----------
 - NEW: uses greylib on low-depth targets!
 - Loadable maps implemented, UNTESTED!
 - Sprites in progress (see render() in graphics.c)

Change-Id: Ia2ff60b3c43d9f2e3a4f63e0ad90d2cb571c605e

1 files changed, 130 insertions, 0 deletions

diff --git a/apps/plugins/xracer/map.c b/apps/plugins/xracer/map.c
new file mode 100644
index 0000000..6900dab
--- /dev/null
+++ b/apps/plugins/xracer/map.c
@@ -0,0 +1,130 @@
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "generator.h"
+#include "map.h"
+#include "util.h"
+
+static bool add_section(struct road_segment *road, unsigned int max_road_length, unsigned int *back, struct road_section *map)
+{
+    bool ret = true;
+    switch(map->type)
+    {
+    case 0:
+        /* constant segment */
+        add_road(road, max_road_length, *back, map->len, map->curve, map->slope);
+        *back += map->len;
+        break;
+    case 1:
+        /* up-hill */
+        add_uphill(road, max_road_length, *back, map->slope, map->len, map->curve);
+        *back += map->len + 2*map->slope;
+        break;
+    case 2:
+        add_downhill(road, max_road_length, *back, map->slope, map->len, map->curve);
+        *back += map->len + 2*map->slope;
+        break;
+    default:
+        warning("invalid type id");
+        ret = false;
+        break;
+    }
+    return ret;
+}
+
+unsigned load_map(struct road_segment *road, unsigned int max_road_length, struct road_section *map, unsigned int map_length)
+{
+    gen_reset();
+    unsigned int back = 0;
+    for(unsigned int i=0;i<map_length;++i)
+    {
+        add_section(road, max_road_length, &back, &map[i]);
+    }
+    return back;
+}
+
+unsigned load_external_map(struct road_segment *road, unsigned int max_road_length, const char *filename)
+{
+    int fd = rb->open(filename, O_RDONLY, 0666);
+    if(fd < 0)
+    {
+        warning("Map file could not be opened");
+        return -1;
+    }
+
+    /* check the header */
+    static const unsigned char cmp_header[8] = {'X', 'M', 'a', 'P',
+                                                ((MAP_VERSION & 0xFF00) >> 8),
+                                                ((MAP_VERSION & 0x00FF) >> 0),
+                                                0xFF, 0xFF };
+    unsigned char header[8];
+    int ret = rb->read(fd, header, sizeof(header));
+    if(ret != sizeof(header) || rb->memcmp(header, cmp_header, sizeof(header)) != 0)
+    {
+        warning("Malformed map header (version mismatch?)");
+        return -1;
+    }
+
+    /* read data */
+    unsigned char data_buf[16];
+    unsigned int back = 0;
+    bool fail = false;
+
+    gen_reset();
+
+    do {
+
+        ret = rb->read(fd, data_buf, sizeof(data_buf));
+        if(ret != sizeof(data_buf))
+        {
+            break;
+        }
+
+        uint16_t calc_crc16 = crc16_ccitt(data_buf, 12, 0, 0xFFFF);
+        uint8_t calc_xor_value = ((calc_crc16 & 0xFF00) >> 8 ) ^ (calc_crc16 & 0xFF);
+
+        uint16_t crc16 = (data_buf[0x0D] << 8) | (data_buf[0x0E]);
+        uint8_t xor_value = data_buf[0x0F];
+        if((calc_crc16 != crc16))
+        {
+            warning("Bad checksum");
+            fail = true;
+        }
+        if(calc_xor_value != xor_value)
+        {
+            warning("Bad XOR value");
+            fail = true;
+        }
+
+        struct road_section section =
+            {
+                data_buf[0],
+                READ_BE_UINT32(&data_buf[1]),
+                READ_BE_UINT32(&data_buf[5]),
+                READ_BE_UINT32(&data_buf[9])
+            };
+
+        bool status = add_section(road, max_road_length, &back, &section);
+
+        if(!status)
+        {
+            warning("Unknown map section type");
+            fail = true;
+        }
+
+    } while(ret == sizeof(data_buf));
+
+    /* last number of bytes read was not zero, this indicates failure */
+    if(ret)
+    {
+        warning("Data too long");
+        fail = true;
+    }
+
+    rb->close(fd);
+
+    if(fail)
+        return -1;
+    else
+        return back;
+}