SHA512Transform
SHA512Transform(H, (uint8_t *)buf + i);
SHA512Transform(H, pad + i);
static void SHA512Transform(SHA2_CTX *, const uint8_t *);
SHA512Transform(ctx, ctx->buf_un.buf8);
SHA512Transform(ctx, &input[i]);
SHA512Transform(H, (uint8_t *)buf + i);
SHA512Transform(H, pad + i);