#include <assert.h>
#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
#include "puzzles.h"
sfree(i->sval);
sfree(cfg);
}
+
+/*
+ * The Mines (among others) game descriptions contain the location of every
+ * mine, and can therefore be used to cheat.
+ *
+ * It would be pointless to attempt to _prevent_ this form of
+ * cheating by encrypting the description, since Mines is
+ * open-source so anyone can find out the encryption key. However,
+ * I think it is worth doing a bit of gentle obfuscation to prevent
+ * _accidental_ spoilers: if you happened to note that the game ID
+ * starts with an F, for example, you might be unable to put the
+ * knowledge of those mines out of your mind while playing. So,
+ * just as discussions of film endings are rot13ed to avoid
+ * spoiling it for people who don't want to be told, we apply a
+ * keyless, reversible, but visually completely obfuscatory masking
+ * function to the mine bitmap.
+ */
+void obfuscate_bitmap(unsigned char *bmp, int bits, int decode)
+{
+ int bytes, firsthalf, secondhalf;
+ struct step {
+ unsigned char *seedstart;
+ int seedlen;
+ unsigned char *targetstart;
+ int targetlen;
+ } steps[2];
+ int i, j;
+
+ /*
+ * My obfuscation algorithm is similar in concept to the OAEP
+ * encoding used in some forms of RSA. Here's a specification
+ * of it:
+ *
+ * + We have a `masking function' which constructs a stream of
+ * pseudorandom bytes from a seed of some number of input
+ * bytes.
+ *
+ * + We pad out our input bit stream to a whole number of
+ * bytes by adding up to 7 zero bits on the end. (In fact
+ * the bitmap passed as input to this function will already
+ * have had this done in practice.)
+ *
+ * + We divide the _byte_ stream exactly in half, rounding the
+ * half-way position _down_. So an 81-bit input string, for
+ * example, rounds up to 88 bits or 11 bytes, and then
+ * dividing by two gives 5 bytes in the first half and 6 in
+ * the second half.
+ *
+ * + We generate a mask from the second half of the bytes, and
+ * XOR it over the first half.
+ *
+ * + We generate a mask from the (encoded) first half of the
+ * bytes, and XOR it over the second half. Any null bits at
+ * the end which were added as padding are cleared back to
+ * zero even if this operation would have made them nonzero.
+ *
+ * To de-obfuscate, the steps are precisely the same except
+ * that the final two are reversed.
+ *
+ * Finally, our masking function. Given an input seed string of
+ * bytes, the output mask consists of concatenating the SHA-1
+ * hashes of the seed string and successive decimal integers,
+ * starting from 0.
+ */
+
+ bytes = (bits + 7) / 8;
+ firsthalf = bytes / 2;
+ secondhalf = bytes - firsthalf;
+
+ steps[decode ? 1 : 0].seedstart = bmp + firsthalf;
+ steps[decode ? 1 : 0].seedlen = secondhalf;
+ steps[decode ? 1 : 0].targetstart = bmp;
+ steps[decode ? 1 : 0].targetlen = firsthalf;
+
+ steps[decode ? 0 : 1].seedstart = bmp;
+ steps[decode ? 0 : 1].seedlen = firsthalf;
+ steps[decode ? 0 : 1].targetstart = bmp + firsthalf;
+ steps[decode ? 0 : 1].targetlen = secondhalf;
+
+ for (i = 0; i < 2; i++) {
+ SHA_State base, final;
+ unsigned char digest[20];
+ char numberbuf[80];
+ int digestpos = 20, counter = 0;
+
+ SHA_Init(&base);
+ SHA_Bytes(&base, steps[i].seedstart, steps[i].seedlen);
+
+ for (j = 0; j < steps[i].targetlen; j++) {
+ if (digestpos >= 20) {
+ sprintf(numberbuf, "%d", counter++);
+ final = base;
+ SHA_Bytes(&final, numberbuf, strlen(numberbuf));
+ SHA_Final(&final, digest);
+ digestpos = 0;
+ }
+ steps[i].targetstart[j] ^= digest[digestpos++];
+ }
+
+ /*
+ * Mask off the pad bits in the final byte after both steps.
+ */
+ if (bits % 8)
+ bmp[bits / 8] &= 0xFF & (0xFF00 >> (bits % 8));
+ }
+}
+
+/* err, yeah, these two pretty much rely on unsigned char being 8 bits.
+ * Platforms where this is not the case probably have bigger problems
+ * than just making these two work, though... */
+char *bin2hex(const unsigned char *in, int inlen)
+{
+ char *ret = snewn(inlen*2 + 1, char), *p = ret;
+ int i;
+
+ for (i = 0; i < inlen*2; i++) {
+ int v = in[i/2];
+ if (i % 2 == 0) v >>= 4;
+ *p++ = "0123456789abcdef"[v & 0xF];
+ }
+ *p = '\0';
+ return ret;
+}
+
+unsigned char *hex2bin(const char *in, int outlen)
+{
+ unsigned char *ret = snewn(outlen, unsigned char);
+ int i;
+
+ memset(ret, 0, outlen*sizeof(unsigned char));
+ for (i = 0; i < outlen*2; i++) {
+ int c = in[i];
+ int v;
+
+ assert(c != 0);
+ if (c >= '0' && c <= '9')
+ v = c - '0';
+ else if (c >= 'a' && c <= 'f')
+ v = c - 'a' + 10;
+ else if (c >= 'A' && c <= 'F')
+ v = c - 'A' + 10;
+ else
+ v = 0;
+
+ ret[i / 2] |= v << (4 * (1 - (i % 2)));
+ }
+ return ret;
+}
+
+void game_mkhighlight_specific(frontend *fe, float *ret,
+ int background, int highlight, int lowlight)
+{
+ float max;
+ int i;
+
+ /*
+ * Drop the background colour so that the highlight is
+ * noticeably brighter than it while still being under 1.
+ */
+ max = ret[background*3];
+ for (i = 1; i < 3; i++)
+ if (ret[background*3+i] > max)
+ max = ret[background*3+i];
+ if (max * 1.2F > 1.0F) {
+ for (i = 0; i < 3; i++)
+ ret[background*3+i] /= (max * 1.2F);
+ }
+
+ for (i = 0; i < 3; i++) {
+ if (highlight >= 0)
+ ret[highlight * 3 + i] = ret[background * 3 + i] * 1.2F;
+ if (lowlight >= 0)
+ ret[lowlight * 3 + i] = ret[background * 3 + i] * 0.8F;
+ }
+}
+
+void game_mkhighlight(frontend *fe, float *ret,
+ int background, int highlight, int lowlight)
+{
+ frontend_default_colour(fe, &ret[background * 3]);
+ game_mkhighlight_specific(fe, ret, background, highlight, lowlight);
+}
+
+static void memswap(void *av, void *bv, int size)
+{
+ char tmpbuf[512];
+ char *a = av, *b = bv;
+
+ while (size > 0) {
+ int thislen = min(size, sizeof(tmpbuf));
+ memcpy(tmpbuf, a, thislen);
+ memcpy(a, b, thislen);
+ memcpy(b, tmpbuf, thislen);
+ a += thislen;
+ b += thislen;
+ size -= thislen;
+ }
+}
+
+void shuffle(void *array, int nelts, int eltsize, random_state *rs)
+{
+ char *carray = (char *)array;
+ int i;
+
+ for (i = nelts; i-- > 1 ;) {
+ int j = random_upto(rs, i+1);
+ if (j != i)
+ memswap(carray + eltsize * i, carray + eltsize * j, eltsize);
+ }
+}
+
+void draw_rect_outline(drawing *dr, int x, int y, int w, int h, int colour)
+{
+ int x0 = x, x1 = x+w-1, y0 = y, y1 = y+h-1;
+ int coords[8];
+
+ coords[0] = x0;
+ coords[1] = y0;
+ coords[2] = x0;
+ coords[3] = y1;
+ coords[4] = x1;
+ coords[5] = y1;
+ coords[6] = x1;
+ coords[7] = y0;
+
+ draw_polygon(dr, coords, 4, -1, colour);
+}
+
+void draw_rect_corners(drawing *dr, int cx, int cy, int r, int col)
+{
+ draw_line(dr, cx - r, cy - r, cx - r, cy - r/2, col);
+ draw_line(dr, cx - r, cy - r, cx - r/2, cy - r, col);
+ draw_line(dr, cx - r, cy + r, cx - r, cy + r/2, col);
+ draw_line(dr, cx - r, cy + r, cx - r/2, cy + r, col);
+ draw_line(dr, cx + r, cy - r, cx + r, cy - r/2, col);
+ draw_line(dr, cx + r, cy - r, cx + r/2, cy - r, col);
+ draw_line(dr, cx + r, cy + r, cx + r, cy + r/2, col);
+ draw_line(dr, cx + r, cy + r, cx + r/2, cy + r, col);
+}
+
+void move_cursor(int button, int *x, int *y, int maxw, int maxh, int wrap)
+{
+ int dx = 0, dy = 0;
+ switch (button) {
+ case CURSOR_UP: dy = -1; break;
+ case CURSOR_DOWN: dy = 1; break;
+ case CURSOR_RIGHT: dx = 1; break;
+ case CURSOR_LEFT: dx = -1; break;
+ default: return;
+ }
+ if (wrap) {
+ *x = (*x + dx + maxw) % maxw;
+ *y = (*y + dy + maxh) % maxh;
+ } else {
+ *x = min(max(*x+dx, 0), maxw - 1);
+ *y = min(max(*y+dy, 0), maxh - 1);
+ }
+}
+
+/* Used in netslide.c and sixteen.c for cursor movement around edge. */
+
+int c2pos(int w, int h, int cx, int cy)
+{
+ if (cy == -1)
+ return cx; /* top row, 0 .. w-1 (->) */
+ else if (cx == w)
+ return w + cy; /* R col, w .. w+h -1 (v) */
+ else if (cy == h)
+ return w + h + (w-cx-1); /* bottom row, w+h .. w+h+w-1 (<-) */
+ else if (cx == -1)
+ return w + h + w + (h-cy-1); /* L col, w+h+w .. w+h+w+h-1 (^) */
+
+ assert(!"invalid cursor pos!");
+ return -1; /* not reached */
+}
+
+int c2diff(int w, int h, int cx, int cy, int button)
+{
+ int diff = 0;
+
+ assert(IS_CURSOR_MOVE(button));
+
+ /* Obvious moves around edge. */
+ if (cy == -1)
+ diff = (button == CURSOR_RIGHT) ? +1 : (button == CURSOR_LEFT) ? -1 : diff;
+ if (cy == h)
+ diff = (button == CURSOR_RIGHT) ? -1 : (button == CURSOR_LEFT) ? +1 : diff;
+ if (cx == -1)
+ diff = (button == CURSOR_UP) ? +1 : (button == CURSOR_DOWN) ? -1 : diff;
+ if (cx == w)
+ diff = (button == CURSOR_UP) ? -1 : (button == CURSOR_DOWN) ? +1 : diff;
+
+ if (button == CURSOR_LEFT && cx == w && (cy == 0 || cy == h-1))
+ diff = (cy == 0) ? -1 : +1;
+ if (button == CURSOR_RIGHT && cx == -1 && (cy == 0 || cy == h-1))
+ diff = (cy == 0) ? +1 : -1;
+ if (button == CURSOR_DOWN && cy == -1 && (cx == 0 || cx == w-1))
+ diff = (cx == 0) ? -1 : +1;
+ if (button == CURSOR_UP && cy == h && (cx == 0 || cx == w-1))
+ diff = (cx == 0) ? +1 : -1;
+
+ debug(("cx,cy = %d,%d; w%d h%d, diff = %d", cx, cy, w, h, diff));
+ return diff;
+}
+
+void pos2c(int w, int h, int pos, int *cx, int *cy)
+{
+ int max = w+h+w+h;
+
+ pos = (pos + max) % max;
+
+ if (pos < w) {
+ *cx = pos; *cy = -1; return;
+ }
+ pos -= w;
+ if (pos < h) {
+ *cx = w; *cy = pos; return;
+ }
+ pos -= h;
+ if (pos < w) {
+ *cx = w-pos-1; *cy = h; return;
+ }
+ pos -= w;
+ if (pos < h) {
+ *cx = -1; *cy = h-pos-1; return;
+ }
+ assert(!"invalid pos, huh?"); /* limited by % above! */
+}
+
+void draw_text_outline(drawing *dr, int x, int y, int fonttype,
+ int fontsize, int align,
+ int text_colour, int outline_colour, char *text)
+{
+ if (outline_colour > -1) {
+ draw_text(dr, x-1, y, fonttype, fontsize, align, outline_colour, text);
+ draw_text(dr, x+1, y, fonttype, fontsize, align, outline_colour, text);
+ draw_text(dr, x, y-1, fonttype, fontsize, align, outline_colour, text);
+ draw_text(dr, x, y+1, fonttype, fontsize, align, outline_colour, text);
+ }
+ draw_text(dr, x, y, fonttype, fontsize, align, text_colour, text);
+
+}
+
+/* kludge for sprintf() in Rockbox not supporting "%-8.8s" */
+void copy_left_justified(char *buf, size_t sz, const char *str)
+{
+ size_t len = strlen(str);
+ assert(sz > 0);
+ memset(buf, ' ', sz - 1);
+ assert(len <= sz - 1);
+ memcpy(buf, str, len);
+ buf[sz - 1] = 0;
+}
+
+/* vim: set shiftwidth=4 tabstop=8: */
~ian / sgt-puzzles.git / blobdiff