Function chacha_block

3rd/mimalloc-2.0.9/src/random.c:51–83

}

static void chacha_block(mi_random_ctx_t* ctx)
{
  // scramble into `x`
  uint32_t x[16];
  for (size_t i = 0; i < 16; i++) {
    x[i] = ctx->input[i];
  }
  for (size_t i = 0; i < MI_CHACHA_ROUNDS; i += 2) {
    qround(x, 0, 4,  8, 12);
    qround(x, 1, 5,  9, 13);
    qround(x, 2, 6, 10, 14);
    qround(x, 3, 7, 11, 15);
    qround(x, 0, 5, 10, 15);
    qround(x, 1, 6, 11, 12);
    qround(x, 2, 7,  8, 13);
    qround(x, 3, 4,  9, 14);
  }

  // add scrambled data to the initial state
  for (size_t i = 0; i < 16; i++) {
    ctx->output[i] = x[i] + ctx->input[i];
  }
  ctx->output_available = 16;

  // increment the counter for the next round
  ctx->input[12] += 1;
  if (ctx->input[12] == 0) {
    ctx->input[13] += 1;
    if (ctx->input[13] == 0) {  // and keep increasing into the nonce
      ctx->input[14] += 1;
    }
  }
}

static uint32_t chacha_next32(mi_random_ctx_t* ctx) {
  if (ctx->output_available <= 0) {