static mrb_value mrb_rand(mrb_state* mrb, mrb_value self)
{
int i;
mrb_value max;
mrb_value seed;
max = get_opt(mrb);
if (mrb_nil_p(self)) {
seed = mrb_gv_get(mrb, mrb_intern_lit(mrb, GLOBAL_RAND_SEED_KEY));
i = NEXT_SEED(seed);
mrb_gv_set(mrb, mrb_intern_lit(mrb, GLOBAL_RAND_SEED_KEY), mrb_fixnum_value(i));
} else {
seed = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, INSTANCE_RAND_SEED_KEY));
i = NEXT_SEED(seed);
mrb_iv_set(mrb, self, mrb_intern_lit(mrb, INSTANCE_RAND_SEED_KEY), mrb_fixnum_value(i));
}
if (mrb_nil_p(max) || mrb_fixnum(max) == 0) {
return mrb_float_value(mrb, NEXT_RAND(i) / 32767.0);
}
return mrb_float_value(mrb, NEXT_RAND(i) % mrb_fixnum(max));
}
//*****************************************************************************
//
// Scroll the tunnel image one column to the left and add a new column of
// tunnel on the right side of the display.
//
//*****************************************************************************
static void
UpdateBackground(unsigned long ulGap)
{
unsigned long ulCount, ulIdx;
//
// Loop through the array of mines.
//
for(ulIdx = 0; ulIdx < 5; ulIdx++)
{
//
// Skip this mine if it is disabled.
//
if((g_pcMines[ulIdx][0] == (char)-1) &&
(g_pcMines[ulIdx][1] == (char)-1) &&
(g_pcMines[ulIdx][2] == (char)-1))
{
continue;
}
//
// Stop searching if this mine is near or on the right side of the
// display.
//
if(g_pcMines[ulIdx][1] > 91)
{
break;
}
}
//
// Get a random number based on the collected entropy.
//
ulCount = RandomNumber();
//
// If the top part of the tunnel is not at the top of the display, then
// move it up 18.75% of the time.
//
if((ulCount < 0x30000000) && (g_pucOffset[0] != 0))
{
g_pucOffset[0]--;
}
//
// If the top part of the tunnel is not too close to the bottom part of the
// tunnel, and there is no mine on the right side of the display or the top
// part of the tunnel is far enough away from the mine, then move it down
// 18.75% of the time.
//
if((ulCount > 0xd0000000) && ((g_pucOffset[0] + ulGap) < g_pucOffset[1]) &&
((ulIdx == 5) || ((g_pcMines[ulIdx][2] - g_pucOffset[0]) > 1)))
{
g_pucOffset[0]++;
}
//
// Get a new pseudo random number based on the original random number (no
// new entropy will have been collected, so it will return the exact same
// random number, which isn't so random).
//
ulCount = NEXT_RAND(ulCount);
//
// If the bottom part of the tunnel is not too close to the top part of the
// tunnel, and there is no mine on the right side of the display or the
// bottom part of the tunnel is far enough away from the mine, then move it
// up 18.75% of the time.
//
if((ulCount < 0x30000000) && ((g_pucOffset[1] - ulGap) > g_pucOffset[0]) &&
((ulIdx == 5) || ((g_pucOffset[1] - g_pcMines[ulIdx][2]) > 5)))
{
g_pucOffset[1]--;
}
//
// If the bottom part of the tunnel is not at the bottom of the display,
// then move it down 18.75% of the time.
//
if((ulCount > 0xd0000000) && (g_pucOffset[1] != 16))
{
g_pucOffset[1]++;
}
//
// Move the background image one column to the left.
//
for(ulCount = 0; ulCount < 192; ulCount++)
{
g_pucBackground[ulCount] = g_pucBackground[ulCount + 1];
}
//
// Generate a new column on the right side of the background image.
//
g_pucBackground[95] = 0xff >> (8 - g_pucOffset[0]);
g_pucBackground[191] = 0xff << (g_pucOffset[1] - 8);
//
// Copy the background image to the local frame buffer.
//
for(ulCount = 0; ulCount < 192; ulCount += 4)
{
*(unsigned long *)(g_pucFrame + ulCount) =
*(unsigned long *)(g_pucBackground + ulCount);
}
}
