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make random number generator more random
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@gltile-two-electric-boogaloo
gltile-two-electric-boogaloo committed May 21, 2022
1 parent 0f3cfad commit 73d255e
Showing 1 changed file with 41 additions and 37 deletions.
78 changes: 41 additions & 37 deletions uwurandom.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1304,46 +1304,50 @@ static string_with_len actions[] = {
STRING_WITH_LEN("*lies down on a random surface*")
};

const size_t RAND_SIZE = 1048576; // 1MiB

uint64_t rol64(uint64_t x, int k) {
return (x << k) | (x >> (64 - k));
}

uint64_t xoshiro256ss(uwu_state *state) {
uint64_t *s = state->rand_state;
uint64_t const result = rol64(s[1] * 5, 7) * 9;
uint64_t const t = s[1] << 17;
static void ensure_randbuf(uwu_state *state, size_t size) {
if (size < (sizeof(uint64_t) - state->rng_idx)) {
uint64_t *s = state->rand_state;
uint64_t const result = rol64(s[1] * 5, 7) * 9;
uint64_t const t = s[1] << 17;

s[2] ^= s[0];
s[3] ^= s[1];
s[1] ^= s[2];
s[0] ^= s[3];
s[2] ^= s[0];
s[3] ^= s[1];
s[1] ^= s[2];
s[0] ^= s[3];

s[2] ^= t;
s[3] = rol64(s[3], 45);
s[2] ^= t;
s[3] = rol64(s[3], 45);

return result;
memcpy(state->rng_buf, &result, sizeof(uint64_t));
state->rng_idx = 0;
}
}

static void get_random_buffered(uwu_state *state, void *dst, size_t size) {
// TODO: handle cases where size is more than 8 bytes
static uint8_t get_random_int(uwu_state *state) {
ensure_randbuf(state, sizeof(uint8_t));

if (size < (sizeof(uint64_t) - state->rng_idx)) {
uint64_t rand = xoshiro256ss(state);
*(state->rng_buf) = rand;
state->rng_idx = 0;
}
memcpy(dst, state->rng_buf + state->rng_idx, size);
state->rng_idx += size;
uint8_t ret = state->rng_buf[state->rng_idx];
state->rng_idx += sizeof(uint8_t);

return ret;
}

static uint16_t get_random_int16(uwu_state *state) {
ensure_randbuf(state, sizeof(uint16_t));

uint16_t ret = state->rng_buf[state->rng_idx];
state->rng_idx += sizeof(uint16_t);

return ret;
}

// Pick a random program from the list of programs and write it to the ops list
static void
generate_new_ops(uwu_state *state) {
// init to 0 in case get_random_bytes fails
unsigned int random = 0;
get_random_buffered(state, &random, sizeof(random));
static void generate_new_ops(uwu_state *state) {
uint8_t random = get_random_int(state);

static uwu_op null_op = {
.opcode = UWU_NULL
Expand Down Expand Up @@ -1372,7 +1376,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 1: { // catgirl nonsense
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
uwu_op op1 = CREATE_PRINT_STRING("mr");
uwu_op op2 = {
.opcode = UWU_MARKOV,
Expand All @@ -1392,7 +1396,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 2: { // nyaaaaaaa
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
uwu_op op1 = CREATE_PRINT_STRING("ny");
uwu_op op2 = CREATE_REPEAT_CHARACTER('a', (random % 7) + 1);
ops[0] = op1;
Expand All @@ -1401,7 +1405,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 3: { // >/////<
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
uwu_op op1 = CREATE_PRINT_STRING(">");
uwu_op op2 = CREATE_REPEAT_CHARACTER('/', (random % 4) + 3);
uwu_op op3 = CREATE_PRINT_STRING("<");
Expand All @@ -1418,7 +1422,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 5: { // actions
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
string_with_len action = actions[random % (sizeof(actions) / sizeof(string_with_len))];
uwu_op op = {
.opcode = UWU_PRINT_STRING,
Expand All @@ -1434,7 +1438,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 6: { // keyboard mash
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
uwu_op op = {
.opcode = UWU_MARKOV,
.state = {
Expand All @@ -1450,7 +1454,7 @@ generate_new_ops(uwu_state *state) {
break;
}
case 7: { // screaming
get_random_buffered(state, &random, sizeof(random));
random = get_random_int(state);
uwu_op op = CREATE_REPEAT_CHARACTER('A', (random % 12) + 5);
ops[0] = op;
ops[1] = null_op;
Expand Down Expand Up @@ -1513,9 +1517,9 @@ static int exec_op(uwu_state *state, char *buf, size_t len) {
int i;
for (i = 0; i < num_chars_to_copy; i++) {
uwu_markov_ngram ngram = ngrams[ngram_index];
unsigned int random = 0;
get_random_buffered(state, &random, sizeof(random));
uint16_t random = get_random_int16(state);
random %= ngram.total_probability;

int j = 0;
while (true) {
uwu_markov_choice choice = ngram.choices[j];
Expand Down Expand Up @@ -1597,7 +1601,7 @@ int main() {
return ENOMEM;
}

char *rng_buf = malloc(RAND_SIZE);
char *rng_buf = malloc(sizeof(uint64_t));

if (rng_buf == NULL) {
fprintf(stderr, "error: out of memory");
Expand All @@ -1608,7 +1612,7 @@ int main() {
data->prev_op = -1;
data->current_op = 0;
data->rng_buf = rng_buf;
data->rng_idx = RAND_SIZE;
data->rng_idx = sizeof(uint64_t);

generate_new_ops(data);

Expand Down

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