ref: bef1b2c59b443a2778a01e6c167e29ee9670603a
dir: /misc.c/
/*
* misc.c: Miscellaneous helpful functions.
*/
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "puzzles.h"
void free_cfg(config_item *cfg)
{
config_item *i;
for (i = cfg; i->type != C_END; i++)
if (i->type == C_STRING)
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);
}
/* vim: set shiftwidth=4 tabstop=8: */