mikunyan/ext/decoders/native/astc.c

#include "astc.h"
#include <math.h>
#include <ruby.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "color.h"
#include "fp16.h"

static const int BitReverseTable[] = {
  0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48,
  0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4,
  0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C,
  0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2,
  0x32, 0xB2, 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A,
  0xFA, 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E,
  0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81, 0x41, 0xC1, 0x21,
  0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9,
  0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55,
  0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD,
  0x7D, 0xFD, 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, 0x0B,
  0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7,
  0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F,
  0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF};

static const int WeightPrecTableA[] = {0, 0, 0, 3, 0, 5, 3, 0, 0, 0, 5, 3, 0, 5, 3, 0};
static const int WeightPrecTableB[] = {0, 0, 1, 0, 2, 0, 1, 3, 0, 0, 1, 2, 4, 2, 3, 5};

static const int CemTableA[] = {0, 3, 5, 0, 3, 5, 0, 3, 5, 0, 3, 5, 0, 3, 5, 0, 3, 0, 0};
static const int CemTableB[] = {8, 6, 5, 7, 5, 4, 6, 4, 3, 5, 3, 2, 4, 2, 1, 3, 1, 2, 1};

static inline uint_fast8_t bit_reverse_u8(const uint_fast8_t c, const int bits) {
    return BitReverseTable[c] >> (8 - bits);
}

static inline uint_fast64_t bit_reverse_u64(const uint_fast64_t d, const int bits) {
    uint_fast64_t ret = (uint_fast64_t)BitReverseTable[d & 0xff] << 56 |
      (uint_fast64_t)BitReverseTable[d >> 8 & 0xff] << 48 | (uint_fast64_t)BitReverseTable[d >> 16 & 0xff] << 40 |
      (uint_fast64_t)BitReverseTable[d >> 24 & 0xff] << 32 | (uint_fast32_t)BitReverseTable[d >> 32 & 0xff] << 24 |
      (uint_fast32_t)BitReverseTable[d >> 40 & 0xff] << 16 | (uint_fast16_t)BitReverseTable[d >> 48 & 0xff] << 8 |
      BitReverseTable[d >> 56 & 0xff];
    return ret >> (64 - bits);
}

static inline int getbits(const uint8_t *buf, const int bit, const int len) {
    return (*(int *)(buf + bit / 8) >> (bit % 8)) & ((1 << len) - 1);
}

static inline uint_fast64_t getbits64(const uint8_t *buf, const int bit, const int len) {
    uint_fast64_t mask = len == 64 ? 0xffffffffffffffff : (1ull << len) - 1;
    if (len < 1)
        return 0;
    else if (bit >= 64)
        return (*(uint_fast64_t *)(buf + 8)) >> (bit - 64) & mask;
    else if (bit <= 0)
        return (*(uint_fast64_t *)buf) << -bit & mask;
    else if (bit + len <= 64)
        return (*(uint_fast64_t *)buf) >> bit & mask;
    else
        return ((*(uint_fast64_t *)buf) >> bit | *(uint_fast64_t *)(buf + 8) << (64 - bit)) & mask;
}

static inline uint16_t u8ptr_to_u16(const uint8_t *ptr) {
    return lton16(*(uint16_t *)ptr);
}

static inline uint_fast8_t clamp(const int n) {
    return n < 0 ? 0 : n > 255 ? 255 : n;
}

static inline void bit_transfer_signed(int *a, int *b) {
    *b = (*b >> 1) | (*a & 0x80);
    *a = (*a >> 1) & 0x3f;
    if (*a & 0x20)
        *a -= 0x40;
}

static inline void set_endpoint(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2, int a2) {
    endpoint[0] = r1;
    endpoint[1] = g1;
    endpoint[2] = b1;
    endpoint[3] = a1;
    endpoint[4] = r2;
    endpoint[5] = g2;
    endpoint[6] = b2;
    endpoint[7] = a2;
}

static inline void set_endpoint_clamp(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2, int a2) {
    endpoint[0] = clamp(r1);
    endpoint[1] = clamp(g1);
    endpoint[2] = clamp(b1);
    endpoint[3] = clamp(a1);
    endpoint[4] = clamp(r2);
    endpoint[5] = clamp(g2);
    endpoint[6] = clamp(b2);
    endpoint[7] = clamp(a2);
}

static inline void set_endpoint_blue(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2, int a2) {
    endpoint[0] = (r1 + b1) >> 1;
    endpoint[1] = (g1 + b1) >> 1;
    endpoint[2] = b1;
    endpoint[3] = a1;
    endpoint[4] = (r2 + b2) >> 1;
    endpoint[5] = (g2 + b2) >> 1;
    endpoint[6] = b2;
    endpoint[7] = a2;
}

static inline void set_endpoint_blue_clamp(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2,
                                           int a2) {
    endpoint[0] = clamp((r1 + b1) >> 1);
    endpoint[1] = clamp((g1 + b1) >> 1);
    endpoint[2] = clamp(b1);
    endpoint[3] = clamp(a1);
    endpoint[4] = clamp((r2 + b2) >> 1);
    endpoint[5] = clamp((g2 + b2) >> 1);
    endpoint[6] = clamp(b2);
    endpoint[7] = clamp(a2);
}

static inline uint_fast16_t clamp_hdr(const int n) {
    return n < 0 ? 0 : n > 0xfff ? 0xfff : n;
}

static inline void set_endpoint_hdr(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2, int a2) {
    endpoint[0] = r1;
    endpoint[1] = g1;
    endpoint[2] = b1;
    endpoint[3] = a1;
    endpoint[4] = r2;
    endpoint[5] = g2;
    endpoint[6] = b2;
    endpoint[7] = a2;
}

static inline void set_endpoint_hdr_clamp(int endpoint[8], int r1, int g1, int b1, int a1, int r2, int g2, int b2,
                                          int a2) {
    endpoint[0] = clamp_hdr(r1);
    endpoint[1] = clamp_hdr(g1);
    endpoint[2] = clamp_hdr(b1);
    endpoint[3] = clamp_hdr(a1);
    endpoint[4] = clamp_hdr(r2);
    endpoint[5] = clamp_hdr(g2);
    endpoint[6] = clamp_hdr(b2);
    endpoint[7] = clamp_hdr(a2);
}

typedef uint_fast8_t (*t_select_folor_func_ptr)(int, int, int);

static uint_fast8_t select_color(int v0, int v1, int weight) {
    return ((((v0 << 8 | v0) * (64 - weight) + (v1 << 8 | v1) * weight + 32) >> 6) * 255 + 32768) / 65536;
}

static uint_fast8_t select_color_hdr(int v0, int v1, int weight) {
    uint16_t c = ((v0 << 4) * (64 - weight) + (v1 << 4) * weight + 32) >> 6;
    uint16_t m = c & 0x7ff;
    if (m < 512)
        m *= 3;
    else if (m < 1536)
        m = 4 * m - 512;
    else
        m = 5 * m - 2048;
    float f = fp16_ieee_to_fp32_value((c >> 1 & 0x7c00) | m >> 3);
    return isfinite(f) ? clamp(roundf(f * 255)) : 255;
}

static inline uint8_t f32_to_u8(const float f) {
    float c = roundf(f * 255);
    if (c < 0)
        return 0;
    else if (c > 255)
        return 255;
    else
        return c;
}

static inline uint8_t f16ptr_to_u8(const uint8_t *ptr) {
    return f32_to_u8(fp16_ieee_to_fp32_value(lton16(*(uint16_t *)ptr)));
}

typedef struct {
    int bw;
    int bh;
    int width;
    int height;
    int part_num;
    int dual_plane;
    int plane_selector;
    int weight_range;
    int weight_num;  // max: 120
    int cem[4];
    int cem_range;
    int endpoint_value_num;  // max: 32
    int endpoints[4][8];
    int weights[144][2];
    int partition[144];
} BlockData;

typedef struct {
    int bits;
    int nonbits;
} IntSeqData;

void decode_intseq(const uint8_t *buf, int offset, const int a, const int b, const int count, const int reverse,
                   IntSeqData *out) {
    static int mt[] = {0, 2, 4, 5, 7};
    static int mq[] = {0, 3, 5};
    static int TritsTable[5][256] = {
      {0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 0, 0,
       1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 1, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1,
       2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2,
       2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0,
       0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0,
       1, 2, 2, 0, 1, 2, 1, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1,
       2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 0, 1, 2, 1, 0, 1, 2, 2, 0, 1, 2, 2},
      {0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
       1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2,
       2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 0, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2,
       0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 0, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1,
       1, 1, 1, 1, 2, 2, 2, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2,
       2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2,
       2, 1, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 1},
      {0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0,
       0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0,
       0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2,
       2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2,
       1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1,
       1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1,
       1, 2, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 2, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 2},
      {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2},
      {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2}};
    static int QuintsTable[3][128] = {
      {0, 1, 2, 3, 4, 0, 4, 4, 0, 1, 2, 3, 4, 1, 4, 4, 0, 1, 2, 3, 4, 2, 4, 4, 0, 1, 2, 3, 4, 3, 4, 4,
       0, 1, 2, 3, 4, 0, 4, 0, 0, 1, 2, 3, 4, 1, 4, 1, 0, 1, 2, 3, 4, 2, 4, 2, 0, 1, 2, 3, 4, 3, 4, 3,
       0, 1, 2, 3, 4, 0, 2, 3, 0, 1, 2, 3, 4, 1, 2, 3, 0, 1, 2, 3, 4, 2, 2, 3, 0, 1, 2, 3, 4, 3, 2, 3,
       0, 1, 2, 3, 4, 0, 0, 1, 0, 1, 2, 3, 4, 1, 0, 1, 0, 1, 2, 3, 4, 2, 0, 1, 0, 1, 2, 3, 4, 3, 0, 1},
      {0, 0, 0, 0, 0, 4, 4, 4, 1, 1, 1, 1, 1, 4, 4, 4, 2, 2, 2, 2, 2, 4, 4, 4, 3, 3, 3, 3, 3, 4, 4, 4,
       0, 0, 0, 0, 0, 4, 0, 4, 1, 1, 1, 1, 1, 4, 1, 4, 2, 2, 2, 2, 2, 4, 2, 4, 3, 3, 3, 3, 3, 4, 3, 4,
       0, 0, 0, 0, 0, 4, 0, 0, 1, 1, 1, 1, 1, 4, 1, 1, 2, 2, 2, 2, 2, 4, 2, 2, 3, 3, 3, 3, 3, 4, 3, 3,
       0, 0, 0, 0, 0, 4, 0, 0, 1, 1, 1, 1, 1, 4, 1, 1, 2, 2, 2, 2, 2, 4, 2, 2, 3, 3, 3, 3, 3, 4, 3, 3},
      {0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 1, 4, 0, 0, 0, 0, 0, 0, 2, 4, 0, 0, 0, 0, 0, 0, 3, 4,
       1, 1, 1, 1, 1, 1, 4, 4, 1, 1, 1, 1, 1, 1, 4, 4, 1, 1, 1, 1, 1, 1, 4, 4, 1, 1, 1, 1, 1, 1, 4, 4,
       2, 2, 2, 2, 2, 2, 4, 4, 2, 2, 2, 2, 2, 2, 4, 4, 2, 2, 2, 2, 2, 2, 4, 4, 2, 2, 2, 2, 2, 2, 4, 4,
       3, 3, 3, 3, 3, 3, 4, 4, 3, 3, 3, 3, 3, 3, 4, 4, 3, 3, 3, 3, 3, 3, 4, 4, 3, 3, 3, 3, 3, 3, 4, 4}};

    if (count <= 0)
        return;

    int n = 0;

    if (a == 3) {
        int mask = (1 << b) - 1;
        int block_count = (count + 4) / 5;
        int last_block_count = (count + 4) % 5 + 1;
        int block_size = 8 + 5 * b;
        int last_block_size = (block_size * last_block_count + 4) / 5;

        if (reverse) {
            for (int i = 0, p = offset; i < block_count; i++, p -= block_size) {
                int now_size = (i < block_count - 1) ? block_size : last_block_size;
                uint_fast64_t d = bit_reverse_u64(getbits64(buf, p - now_size, now_size), now_size);
                int x =
                  (d >> b & 3) | (d >> b * 2 & 0xc) | (d >> b * 3 & 0x10) | (d >> b * 4 & 0x60) | (d >> b * 5 & 0x80);
                for (int j = 0; j < 5 && n < count; j++, n++)
                    out[n] = (IntSeqData){d >> (mt[j] + b * j) & mask, TritsTable[j][x]};
            }
        } else {
            for (int i = 0, p = offset; i < block_count; i++, p += block_size) {
                uint_fast64_t d = getbits64(buf, p, (i < block_count - 1) ? block_size : last_block_size);
                int x =
                  (d >> b & 3) | (d >> b * 2 & 0xc) | (d >> b * 3 & 0x10) | (d >> b * 4 & 0x60) | (d >> b * 5 & 0x80);
                for (int j = 0; j < 5 && n < count; j++, n++)
                    out[n] = (IntSeqData){d >> (mt[j] + b * j) & mask, TritsTable[j][x]};
            }
        }
    } else if (a == 5) {
        int mask = (1 << b) - 1;
        int block_count = (count + 2) / 3;
        int last_block_count = (count + 2) % 3 + 1;
        int block_size = 7 + 3 * b;
        int last_block_size = (block_size * last_block_count + 2) / 3;

        if (reverse) {
            for (int i = 0, p = offset; i < block_count; i++, p -= block_size) {
                int now_size = (i < block_count - 1) ? block_size : last_block_size;
                uint_fast64_t d = bit_reverse_u64(getbits64(buf, p - now_size, now_size), now_size);
                int x = (d >> b & 7) | (d >> b * 2 & 0x18) | (d >> b * 3 & 0x60);
                for (int j = 0; j < 3 && n < count; j++, n++)
                    out[n] = (IntSeqData){d >> (mq[j] + b * j) & mask, QuintsTable[j][x]};
            }
        } else {
            for (int i = 0, p = offset; i < block_count; i++, p += block_size) {
                uint_fast64_t d = getbits64(buf, p, (i < block_count - 1) ? block_size : last_block_size);
                int x = (d >> b & 7) | (d >> b * 2 & 0x18) | (d >> b * 3 & 0x60);
                for (int j = 0; j < 3 && n < count; j++, n++)
                    out[n] = (IntSeqData){d >> (mq[j] + b * j) & mask, QuintsTable[j][x]};
            }
        }
    } else {
        if (reverse)
            for (int p = offset - b; n < count; n++, p -= b)
                out[n] = (IntSeqData){bit_reverse_u8(getbits(buf, p, b), b), 0};
        else
            for (int p = offset; n < count; n++, p += b)
                out[n] = (IntSeqData){getbits(buf, p, b), 0};
    }
}

void decode_block_params(const uint8_t *buf, BlockData *block_data) {
    block_data->dual_plane = !!(buf[1] & 4);
    block_data->weight_range = (buf[0] >> 4 & 1) | (buf[1] << 2 & 8);

    if (buf[0] & 3) {
        // ← W | H H | ρ0 | ? | ? | ρ2 | ρ1
        block_data->weight_range |= buf[0] << 1 & 6;
        switch (buf[0] & 0xc) {
        case 0:
            block_data->width = (u8ptr_to_u16(buf) >> 7 & 3) + 4;
            block_data->height = (buf[0] >> 5 & 3) + 2;
            break;
        case 4:
            block_data->width = (u8ptr_to_u16(buf) >> 7 & 3) + 8;
            block_data->height = (buf[0] >> 5 & 3) + 2;
            break;
        case 8:
            block_data->width = (buf[0] >> 5 & 3) + 2;
            block_data->height = (u8ptr_to_u16(buf) >> 7 & 3) + 8;
            break;
        case 12:
            if (buf[1] & 1) {
                block_data->width = (buf[0] >> 7 & 1) + 2;
                block_data->height = (buf[0] >> 5 & 3) + 2;
            } else {
                block_data->width = (buf[0] >> 5 & 3) + 2;
                block_data->height = (buf[0] >> 7 & 1) + 6;
            }
            break;
        }
    } else {
        // ← W | H H | ρ0 | ρ2 | ρ1 | 0 | 0
        block_data->weight_range |= buf[0] >> 1 & 6;
        switch (u8ptr_to_u16(buf) & 0x180) {
        case 0:
            block_data->width = 12;
            block_data->height = (buf[0] >> 5 & 3) + 2;
            break;
        case 0x80:
            block_data->width = (buf[0] >> 5 & 3) + 2;
            block_data->height = 12;
            break;
        case 0x100:
            block_data->width = (buf[0] >> 5 & 3) + 6;
            block_data->height = (buf[1] >> 1 & 3) + 6;
            block_data->dual_plane = 0;
            block_data->weight_range &= 7;
            break;
        case 0x180:
            block_data->width = (buf[0] & 0x20) ? 10 : 6;
            block_data->height = (buf[0] & 0x20) ? 6 : 10;
            break;
        }
    }

    block_data->part_num = (buf[1] >> 3 & 3) + 1;

    block_data->weight_num = block_data->width * block_data->height;
    if (block_data->dual_plane)
        block_data->weight_num *= 2;

    int weight_bits, config_bits, cem_base = 0;

    switch (WeightPrecTableA[block_data->weight_range]) {
    case 3:
        weight_bits =
          block_data->weight_num * WeightPrecTableB[block_data->weight_range] + (block_data->weight_num * 8 + 4) / 5;
        break;
    case 5:
        weight_bits =
          block_data->weight_num * WeightPrecTableB[block_data->weight_range] + (block_data->weight_num * 7 + 2) / 3;
        break;
    default:
        weight_bits = block_data->weight_num * WeightPrecTableB[block_data->weight_range];
    }

    if (block_data->part_num == 1) {
        block_data->cem[0] = u8ptr_to_u16(buf + 1) >> 5 & 0xf;
        config_bits = 17;
    } else {
        cem_base = u8ptr_to_u16(buf + 2) >> 7 & 3;
        if (cem_base == 0) {
            int cem = buf[3] >> 1 & 0xf;
            for (int i = 0; i < block_data->part_num; i++)
                block_data->cem[i] = cem;
            config_bits = 29;
        } else {
            for (int i = 0; i < block_data->part_num; i++)
                block_data->cem[i] = ((buf[3] >> (i + 1) & 1) + cem_base - 1) << 2;
            switch (block_data->part_num) {
            case 2:
                block_data->cem[0] |= buf[3] >> 3 & 3;
                block_data->cem[1] |= getbits(buf, 126 - weight_bits, 2);
                break;
            case 3:
                block_data->cem[0] |= buf[3] >> 4 & 1;
                block_data->cem[0] |= getbits(buf, 122 - weight_bits, 2) & 2;
                block_data->cem[1] |= getbits(buf, 124 - weight_bits, 2);
                block_data->cem[2] |= getbits(buf, 126 - weight_bits, 2);
                break;
            case 4:
                for (int i = 0; i < 4; i++)
                    block_data->cem[i] |= getbits(buf, 120 + i * 2 - weight_bits, 2);
                break;
            }
            config_bits = 25 + block_data->part_num * 3;
        }
    }

    if (block_data->dual_plane) {
        config_bits += 2;
        block_data->plane_selector =
          getbits(buf, cem_base ? 130 - weight_bits - block_data->part_num * 3 : 126 - weight_bits, 2);
    }

    int remain_bits = 128 - config_bits - weight_bits;

    block_data->endpoint_value_num = 0;
    for (int i = 0; i < block_data->part_num; i++)
        block_data->endpoint_value_num += (block_data->cem[i] >> 1 & 6) + 2;

    for (int i = 0, endpoint_bits; i < (int)(sizeof(CemTableA) / sizeof(int)); i++) {
        switch (CemTableA[i]) {
        case 3:
            endpoint_bits =
              block_data->endpoint_value_num * CemTableB[i] + (block_data->endpoint_value_num * 8 + 4) / 5;
            break;
        case 5:
            endpoint_bits =
              block_data->endpoint_value_num * CemTableB[i] + (block_data->endpoint_value_num * 7 + 2) / 3;
            break;
        default:
            endpoint_bits = block_data->endpoint_value_num * CemTableB[i];
        }

        if (endpoint_bits <= remain_bits) {
            block_data->cem_range = i;
            break;
        }
    }
}

void decode_endpoints_hdr7(int *endpoints, int *v) {
    int modeval = (v[2] >> 4 & 0x8) | (v[1] >> 5 & 0x4) | (v[0] >> 6);
    int major_component, mode;
    if ((modeval & 0xc) != 0xc) {
        major_component = modeval >> 2;
        mode = modeval & 3;
    } else if (modeval != 0xf) {
        major_component = modeval & 3;
        mode = 4;
    } else {
        major_component = 0;
        mode = 5;
    }
    int c[] = {v[0] & 0x3f, v[1] & 0x1f, v[2] & 0x1f, v[3] & 0x1f};

    switch (mode) {
    case 0:
        c[3] |= v[3] & 0x60;
        c[0] |= v[3] >> 1 & 0x40;
        c[0] |= v[2] << 1 & 0x80;
        c[0] |= v[1] << 3 & 0x300;
        c[0] |= v[2] << 5 & 0x400;
        c[0] <<= 1;
        c[1] <<= 1;
        c[2] <<= 1;
        c[3] <<= 1;
        break;
    case 1:
        c[1] |= v[1] & 0x20;
        c[2] |= v[2] & 0x20;
        c[0] |= v[3] >> 1 & 0x40;
        c[0] |= v[2] << 1 & 0x80;
        c[0] |= v[1] << 2 & 0x100;
        c[0] |= v[3] << 4 & 0x600;
        c[0] <<= 1;
        c[1] <<= 1;
        c[2] <<= 1;
        c[3] <<= 1;
        break;
    case 2:
        c[3] |= v[3] & 0xe0;
        c[0] |= v[2] << 1 & 0xc0;
        c[0] |= v[1] << 3 & 0x300;
        c[0] <<= 2;
        c[1] <<= 2;
        c[2] <<= 2;
        c[3] <<= 2;
        break;
    case 3:
        c[1] |= v[1] & 0x20;
        c[2] |= v[2] & 0x20;
        c[3] |= v[3] & 0x60;
        c[0] |= v[3] >> 1 & 0x40;
        c[0] |= v[2] << 1 & 0x80;
        c[0] |= v[1] << 2 & 0x100;
        c[0] <<= 3;
        c[1] <<= 3;
        c[2] <<= 3;
        c[3] <<= 3;
        break;
    case 4:
        c[1] |= v[1] & 0x60;
        c[2] |= v[2] & 0x60;
        c[3] |= v[3] & 0x20;
        c[0] |= v[3] >> 1 & 0x40;
        c[0] |= v[3] << 1 & 0x80;
        c[0] <<= 4;
        c[1] <<= 4;
        c[2] <<= 4;
        c[3] <<= 4;
        break;
    case 5:
        c[1] |= v[1] & 0x60;
        c[2] |= v[2] & 0x60;
        c[3] |= v[3] & 0x60;
        c[0] |= v[3] >> 1 & 0x40;
        c[0] <<= 5;
        c[1] <<= 5;
        c[2] <<= 5;
        c[3] <<= 5;
        break;
    }
    if (mode != 5) {
        c[1] = c[0] - c[1];
        c[2] = c[0] - c[2];
    }
    if (major_component == 1)
        set_endpoint_hdr_clamp(endpoints, c[1] - c[3], c[0] - c[3], c[2] - c[3], 0x780, c[1], c[0], c[2], 0x780);
    else if (major_component == 2)
        set_endpoint_hdr_clamp(endpoints, c[2] - c[3], c[1] - c[3], c[0] - c[3], 0x780, c[2], c[1], c[0], 0x780);
    else
        set_endpoint_hdr_clamp(endpoints, c[0] - c[3], c[1] - c[3], c[2] - c[3], 0x780, c[0], c[1], c[2], 0x780);
}

void decode_endpoints_hdr11(int *endpoints, int *v, int alpha1, int alpha2) {
    int major_component = (v[4] >> 7) | (v[5] >> 6 & 2);
    if (major_component == 3) {
        set_endpoint_hdr(endpoints, v[0] << 4, v[2] << 4, v[4] << 5 & 0xfe0, alpha1, v[1] << 4, v[3] << 4,
                         v[5] << 5 & 0xfe0, alpha2);
        return;
    }
    int mode = (v[1] >> 7) | (v[2] >> 6 & 2) | (v[3] >> 5 & 4);
    int va = v[0] | (v[1] << 2 & 0x100);
    int vb0 = v[2] & 0x3f, vb1 = v[3] & 0x3f;
    int vc = v[1] & 0x3f;
    int16_t vd0, vd1;

    switch (mode) {
    case 0:
    case 2:
        vd0 = v[4] & 0x7f;
        if (vd0 & 0x40)
            vd0 |= 0xff80;
        vd1 = v[5] & 0x7f;
        if (vd1 & 0x40)
            vd1 |= 0xff80;
        break;
    case 1:
    case 3:
    case 5:
    case 7:
        vd0 = v[4] & 0x3f;
        if (vd0 & 0x20)
            vd0 |= 0xffc0;
        vd1 = v[5] & 0x3f;
        if (vd1 & 0x20)
            vd1 |= 0xffc0;
        break;
    default:
        vd0 = v[4] & 0x1f;
        if (vd0 & 0x10)
            vd0 |= 0xffe0;
        vd1 = v[5] & 0x1f;
        if (vd1 & 0x10)
            vd1 |= 0xffe0;
        break;
    }

    switch (mode) {
    case 0:
        vb0 |= v[2] & 0x40;
        vb1 |= v[3] & 0x40;
        break;
    case 1:
        vb0 |= v[2] & 0x40;
        vb1 |= v[3] & 0x40;
        vb0 |= v[4] << 1 & 0x80;
        vb1 |= v[5] << 1 & 0x80;
        break;
    case 2:
        va |= v[2] << 3 & 0x200;
        vc |= v[3] & 0x40;
        break;
    case 3:
        va |= v[4] << 3 & 0x200;
        vc |= v[5] & 0x40;
        vb0 |= v[2] & 0x40;
        vb1 |= v[3] & 0x40;
        break;
    case 4:
        va |= v[4] << 4 & 0x200;
        va |= v[5] << 5 & 0x400;
        vb0 |= v[2] & 0x40;
        vb1 |= v[3] & 0x40;
        vb0 |= v[4] << 1 & 0x80;
        vb1 |= v[5] << 1 & 0x80;
        break;
    case 5:
        va |= v[2] << 3 & 0x200;
        va |= v[3] << 4 & 0x400;
        vc |= v[5] & 0x40;
        vc |= v[4] << 1 & 0x80;
        break;
    case 6:
        va |= v[4] << 4 & 0x200;
        va |= v[5] << 5 & 0x400;
        va |= v[4] << 5 & 0x800;
        vc |= v[5] & 0x40;
        vb0 |= v[2] & 0x40;
        vb1 |= v[3] & 0x40;
        break;
    case 7:
        va |= v[2] << 3 & 0x200;
        va |= v[3] << 4 & 0x400;
        va |= v[4] << 5 & 0x800;
        vc |= v[5] & 0x40;
        break;
    }

    int shamt = (mode >> 1) ^ 3;
    va <<= shamt;
    vb0 <<= shamt;
    vb1 <<= shamt;
    vc <<= shamt;
    int mult = 1 << shamt;
    vd0 *= mult;
    vd1 *= mult;

    if (major_component == 1)
        set_endpoint_hdr_clamp(endpoints, va - vb0 - vc - vd0, va - vc, va - vb1 - vc - vd1, alpha1, va - vb0, va,
                               va - vb1, alpha2);
    else if (major_component == 2)
        set_endpoint_hdr_clamp(endpoints, va - vb1 - vc - vd1, va - vb0 - vc - vd0, va - vc, alpha1, va - vb1, va - vb0,
                               va, alpha2);
    else
        set_endpoint_hdr_clamp(endpoints, va - vc, va - vb0 - vc - vd0, va - vb1 - vc - vd1, alpha1, va, va - vb0,
                               va - vb1, alpha2);
}

void decode_endpoints(const uint8_t *buf, BlockData *data) {
    static const int TritsTable[] = {0, 204, 93, 44, 22, 11, 5};
    static const int QuintsTable[] = {0, 113, 54, 26, 13, 6};
    IntSeqData seq[32];
    int ev[32];
    decode_intseq(buf, data->part_num == 1 ? 17 : 29, CemTableA[data->cem_range], CemTableB[data->cem_range],
                  data->endpoint_value_num, 0, seq);

    switch (CemTableA[data->cem_range]) {
    case 3:
        for (int i = 0, b, c = TritsTable[CemTableB[data->cem_range]]; i < data->endpoint_value_num; i++) {
            int a = (seq[i].bits & 1) * 0x1ff;
            int x = seq[i].bits >> 1;
            switch (CemTableB[data->cem_range]) {
            case 1:
                b = 0;
                break;
            case 2:
                b = 0b100010110 * x;
                break;
            case 3:
                b = x << 7 | x << 2 | x;
                break;
            case 4:
                b = x << 6 | x;
                break;
            case 5:
                b = x << 5 | x >> 2;
                break;
            case 6:
                b = x << 4 | x >> 4;
                break;
            }
            ev[i] = (a & 0x80) | ((seq[i].nonbits * c + b) ^ a) >> 2;
        }
        break;
    case 5:
        for (int i = 0, b, c = QuintsTable[CemTableB[data->cem_range]]; i < data->endpoint_value_num; i++) {
            int a = (seq[i].bits & 1) * 0x1ff;
            int x = seq[i].bits >> 1;
            switch (CemTableB[data->cem_range]) {
            case 1:
                b = 0;
                break;
            case 2:
                b = 0b100001100 * x;
                break;
            case 3:
                b = x << 7 | x << 1 | x >> 1;
                break;
            case 4:
                b = x << 6 | x >> 1;
                break;
            case 5:
                b = x << 5 | x >> 3;
                break;
            }
            ev[i] = (a & 0x80) | ((seq[i].nonbits * c + b) ^ a) >> 2;
        }
        break;
    default:
        switch (CemTableB[data->cem_range]) {
        case 1:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits * 0xff;
            break;
        case 2:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits * 0x55;
            break;
        case 3:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits << 5 | seq[i].bits << 2 | seq[i].bits >> 1;
            break;
        case 4:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits << 4 | seq[i].bits;
            break;
        case 5:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits << 3 | seq[i].bits >> 2;
            break;
        case 6:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits << 2 | seq[i].bits >> 4;
            break;
        case 7:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits << 1 | seq[i].bits >> 6;
            break;
        case 8:
            for (int i = 0; i < data->endpoint_value_num; i++)
                ev[i] = seq[i].bits;
            break;
        }
    }

    int *v = ev;
    for (int cem = 0; cem < data->part_num; v += (data->cem[cem] / 4 + 1) * 2, cem++) {
        switch (data->cem[cem]) {
        case 0:
            set_endpoint(data->endpoints[cem], v[0], v[0], v[0], 255, v[1], v[1], v[1], 255);
            break;
        case 1: {
            int l0 = (v[0] >> 2) | (v[1] & 0xc0);
            int l1 = clamp(l0 + (v[1] & 0x3f));
            set_endpoint(data->endpoints[cem], l0, l0, l0, 255, l1, l1, l1, 255);
        } break;
        case 2: {
            int y0, y1;
            if (v[0] <= v[1]) {
                y0 = v[0] << 4;
                y1 = v[1] << 4;
            } else {
                y0 = (v[1] << 4) + 8;
                y1 = (v[0] << 4) - 8;
            }
            set_endpoint_hdr(data->endpoints[cem], y0, y0, y0, 0x780, y1, y1, y1, 0x780);
        } break;
        case 3: {
            int y0, d;
            if (v[0] & 0x80) {
                y0 = (v[1] & 0xe0) << 4 | (v[0] & 0x7f) << 2;
                d = (v[1] & 0x1f) << 2;
            } else {
                y0 = (v[1] & 0xf0) << 4 | (v[0] & 0x7f) << 1;
                d = (v[1] & 0x0f) << 1;
            }
            int y1 = clamp_hdr(y0 + d);
            set_endpoint_hdr(data->endpoints[cem], y0, y0, y0, 0x780, y1, y1, y1, 0x780);
        } break;
        case 4:
            set_endpoint(data->endpoints[cem], v[0], v[0], v[0], v[2], v[1], v[1], v[1], v[3]);
            break;
        case 5:
            bit_transfer_signed(&v[1], &v[0]);
            bit_transfer_signed(&v[3], &v[2]);
            v[1] += v[0];
            set_endpoint_clamp(data->endpoints[cem], v[0], v[0], v[0], v[2], v[1], v[1], v[1], v[2] + v[3]);
            break;
        case 6:
            set_endpoint(data->endpoints[cem], v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8, 255, v[0], v[1],
                         v[2], 255);
            break;
        case 7:
            decode_endpoints_hdr7(data->endpoints[cem], v);
            break;
        case 8:
            if (v[0] + v[2] + v[4] <= v[1] + v[3] + v[5])
                set_endpoint(data->endpoints[cem], v[0], v[2], v[4], 255, v[1], v[3], v[5], 255);
            else
                set_endpoint_blue(data->endpoints[cem], v[1], v[3], v[5], 255, v[0], v[2], v[4], 255);
            break;
        case 9:
            bit_transfer_signed(&v[1], &v[0]);
            bit_transfer_signed(&v[3], &v[2]);
            bit_transfer_signed(&v[5], &v[4]);
            if (v[1] + v[3] + v[5] >= 0)
                set_endpoint_clamp(data->endpoints[cem], v[0], v[2], v[4], 255, v[0] + v[1], v[2] + v[3], v[4] + v[5],
                                   255);
            else
                set_endpoint_blue_clamp(data->endpoints[cem], v[0] + v[1], v[2] + v[3], v[4] + v[5], 255, v[0], v[2],
                                        v[4], 255);
            break;
        case 10:
            set_endpoint(data->endpoints[cem], v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8, v[4], v[0], v[1],
                         v[2], v[5]);
            break;
        case 11:
            decode_endpoints_hdr11(data->endpoints[cem], v, 0x780, 0x780);
            break;
        case 12:
            if (v[0] + v[2] + v[4] <= v[1] + v[3] + v[5])
                set_endpoint(data->endpoints[cem], v[0], v[2], v[4], v[6], v[1], v[3], v[5], v[7]);
            else
                set_endpoint_blue(data->endpoints[cem], v[1], v[3], v[5], v[7], v[0], v[2], v[4], v[6]);
            break;
        case 13:
            bit_transfer_signed(&v[1], &v[0]);
            bit_transfer_signed(&v[3], &v[2]);
            bit_transfer_signed(&v[5], &v[4]);
            bit_transfer_signed(&v[7], &v[6]);
            if (v[1] + v[3] + v[5] >= 0)
                set_endpoint_clamp(data->endpoints[cem], v[0], v[2], v[4], v[6], v[0] + v[1], v[2] + v[3], v[4] + v[5],
                                   v[6] + v[7]);
            else
                set_endpoint_blue_clamp(data->endpoints[cem], v[0] + v[1], v[2] + v[3], v[4] + v[5], v[6] + v[7], v[0],
                                        v[2], v[4], v[6]);
            break;
        case 14:
            decode_endpoints_hdr11(data->endpoints[cem], v, v[6], v[7]);
            break;
        case 15: {
            int mode = ((v[6] >> 7) & 1) | ((v[7] >> 6) & 2);
            v[6] &= 0x7f;
            v[7] &= 0x7f;
            if (mode == 3) {
                decode_endpoints_hdr11(data->endpoints[cem], v, v[6] << 5, v[7] << 5);
            } else {
                v[6] |= (v[7] << (mode + 1)) & 0x780;
                v[7] = ((v[7] & (0x3f >> mode)) ^ (0x20 >> mode)) - (0x20 >> mode);
                v[6] <<= 4 - mode;
                v[7] <<= 4 - mode;
                decode_endpoints_hdr11(data->endpoints[cem], v, v[6], clamp_hdr(v[6] + v[7]));
            }
        } break;
        default:
            rb_raise(rb_eStandardError, "Unsupported ASTC format");
        }
    }
}

void decode_weights(const uint8_t *buf, BlockData *data) {
    IntSeqData seq[128];
    int wv[128] = {};
    decode_intseq(buf, 128, WeightPrecTableA[data->weight_range], WeightPrecTableB[data->weight_range],
                  data->weight_num, 1, seq);

    if (WeightPrecTableA[data->weight_range] == 0) {
        switch (WeightPrecTableB[data->weight_range]) {
        case 1:
            for (int i = 0; i < data->weight_num; i++)
                wv[i] = seq[i].bits ? 63 : 0;
            break;
        case 2:
            for (int i = 0; i < data->weight_num; i++)
                wv[i] = seq[i].bits << 4 | seq[i].bits << 2 | seq[i].bits;
            break;
        case 3:
            for (int i = 0; i < data->weight_num; i++)
                wv[i] = seq[i].bits << 3 | seq[i].bits;
            break;
        case 4:
            for (int i = 0; i < data->weight_num; i++)
                wv[i] = seq[i].bits << 2 | seq[i].bits >> 2;
            break;
        case 5:
            for (int i = 0; i < data->weight_num; i++)
                wv[i] = seq[i].bits << 1 | seq[i].bits >> 4;
            break;
        }
        for (int i = 0; i < data->weight_num; i++)
            if (wv[i] > 32)
                ++wv[i];
    } else if (WeightPrecTableB[data->weight_range] == 0) {
        int s = WeightPrecTableA[data->weight_range] == 3 ? 32 : 16;
        for (int i = 0; i < data->weight_num; i++)
            wv[i] = seq[i].nonbits * s;
    } else {
        if (WeightPrecTableA[data->weight_range] == 3) {
            switch (WeightPrecTableB[data->weight_range]) {
            case 1:
                for (int i = 0; i < data->weight_num; i++)
                    wv[i] = seq[i].nonbits * 50;
                break;
            case 2:
                for (int i = 0; i < data->weight_num; i++) {
                    wv[i] = seq[i].nonbits * 23;
                    if (seq[i].bits & 2)
                        wv[i] += 0b1000101;
                }
                break;
            case 3:
                for (int i = 0; i < data->weight_num; i++)
                    wv[i] = seq[i].nonbits * 11 + ((seq[i].bits << 4 | seq[i].bits >> 1) & 0b1100011);
                break;
            }
        } else if (WeightPrecTableA[data->weight_range] == 5) {
            switch (WeightPrecTableB[data->weight_range]) {
            case 1:
                for (int i = 0; i < data->weight_num; i++)
                    wv[i] = seq[i].nonbits * 28;
                break;
            case 2:
                for (int i = 0; i < data->weight_num; i++) {
                    wv[i] = seq[i].nonbits * 13;
                    if (seq[i].bits & 2)
                        wv[i] += 0b1000010;
                }
                break;
            }
        }
        for (int i = 0; i < data->weight_num; i++) {
            int a = (seq[i].bits & 1) * 0x7f;
            wv[i] = (a & 0x20) | ((wv[i] ^ a) >> 2);
            if (wv[i] > 32)
                ++wv[i];
        }
    }

    int ds = (1024 + data->bw / 2) / (data->bw - 1);
    int dt = (1024 + data->bh / 2) / (data->bh - 1);
    int pn = data->dual_plane ? 2 : 1;

    for (int t = 0, i = 0; t < data->bh; t++) {
        for (int s = 0; s < data->bw; s++, i++) {
            int gs = (ds * s * (data->width - 1) + 32) >> 6;
            int gt = (dt * t * (data->height - 1) + 32) >> 6;
            int fs = gs & 0xf;
            int ft = gt & 0xf;
            int v = (gs >> 4) + (gt >> 4) * data->width;
            int w11 = (fs * ft + 8) >> 4;
            int w10 = ft - w11;
            int w01 = fs - w11;
            int w00 = 16 - fs - ft + w11;

            for (int p = 0; p < pn; p++) {
                int p00 = wv[v * pn + p];
                int p01 = wv[(v + 1) * pn + p];
                int p10 = wv[(v + data->width) * pn + p];
                int p11 = wv[(v + data->width + 1) * pn + p];
                data->weights[i][p] = (p00 * w00 + p01 * w01 + p10 * w10 + p11 * w11 + 8) >> 4;
            }
        }
    }
}

void select_partition(const uint8_t *buf, BlockData *data) {
    int small_block = data->bw * data->bh < 31;
    int seed = (*(int *)buf >> 13 & 0x3ff) | (data->part_num - 1) << 10;

    uint32_t rnum = seed;
    rnum ^= rnum >> 15;
    rnum -= rnum << 17;
    rnum += rnum << 7;
    rnum += rnum << 4;
    rnum ^= rnum >> 5;
    rnum += rnum << 16;
    rnum ^= rnum >> 7;
    rnum ^= rnum >> 3;
    rnum ^= rnum << 6;
    rnum ^= rnum >> 17;

    int seeds[8];
    for (int i = 0; i < 8; i++) {
        seeds[i] = (rnum >> (i * 4)) & 0xF;
        seeds[i] *= seeds[i];
    }

    int sh[2] = {seed & 2 ? 4 : 5, data->part_num == 3 ? 6 : 5};

    if (seed & 1)
        for (int i = 0; i < 8; i++)
            seeds[i] >>= sh[i % 2];
    else
        for (int i = 0; i < 8; i++)
            seeds[i] >>= sh[1 - i % 2];

    if (small_block) {
        for (int t = 0, i = 0; t < data->bh; t++) {
            for (int s = 0; s < data->bw; s++, i++) {
                int x = s << 1;
                int y = t << 1;
                int a = (seeds[0] * x + seeds[1] * y + (rnum >> 14)) & 0x3f;
                int b = (seeds[2] * x + seeds[3] * y + (rnum >> 10)) & 0x3f;
                int c = data->part_num < 3 ? 0 : (seeds[4] * x + seeds[5] * y + (rnum >> 6)) & 0x3f;
                int d = data->part_num < 4 ? 0 : (seeds[6] * x + seeds[7] * y + (rnum >> 2)) & 0x3f;
                data->partition[i] = (a >= b && a >= c && a >= d) ? 0 : (b >= c && b >= d) ? 1 : (c >= d) ? 2 : 3;
            }
        }
    } else {
        for (int y = 0, i = 0; y < data->bh; y++) {
            for (int x = 0; x < data->bw; x++, i++) {
                int a = (seeds[0] * x + seeds[1] * y + (rnum >> 14)) & 0x3f;
                int b = (seeds[2] * x + seeds[3] * y + (rnum >> 10)) & 0x3f;
                int c = data->part_num < 3 ? 0 : (seeds[4] * x + seeds[5] * y + (rnum >> 6)) & 0x3f;
                int d = data->part_num < 4 ? 0 : (seeds[6] * x + seeds[7] * y + (rnum >> 2)) & 0x3f;
                data->partition[i] = (a >= b && a >= c && a >= d) ? 0 : (b >= c && b >= d) ? 1 : (c >= d) ? 2 : 3;
            }
        }
    }
}

void applicate_color(const BlockData *data, uint32_t *outbuf) {
    static const t_select_folor_func_ptr FuncTableC[] = {
      select_color, select_color,     select_color_hdr, select_color_hdr, select_color, select_color,
      select_color, select_color_hdr, select_color,     select_color,     select_color, select_color_hdr,
      select_color, select_color,     select_color_hdr, select_color_hdr};
    static const t_select_folor_func_ptr FuncTableA[] = {
      select_color, select_color,     select_color_hdr, select_color_hdr, select_color, select_color,
      select_color, select_color_hdr, select_color,     select_color,     select_color, select_color_hdr,
      select_color, select_color,     select_color,     select_color_hdr};
    if (data->dual_plane) {
        int ps[] = {0, 0, 0, 0};
        ps[data->plane_selector] = 1;
        if (data->part_num > 1) {
            for (int i = 0; i < data->bw * data->bh; i++) {
                int p = data->partition[i];
                uint_fast8_t r =
                  FuncTableC[data->cem[p]](data->endpoints[p][0], data->endpoints[p][4], data->weights[i][ps[0]]);
                uint_fast8_t g =
                  FuncTableC[data->cem[p]](data->endpoints[p][1], data->endpoints[p][5], data->weights[i][ps[1]]);
                uint_fast8_t b =
                  FuncTableC[data->cem[p]](data->endpoints[p][2], data->endpoints[p][6], data->weights[i][ps[2]]);
                uint_fast8_t a =
                  FuncTableA[data->cem[p]](data->endpoints[p][3], data->endpoints[p][7], data->weights[i][ps[3]]);
                outbuf[i] = color(r, g, b, a);
            }
        } else {
            for (int i = 0; i < data->bw * data->bh; i++) {
                uint_fast8_t r =
                  FuncTableC[data->cem[0]](data->endpoints[0][0], data->endpoints[0][4], data->weights[i][ps[0]]);
                uint_fast8_t g =
                  FuncTableC[data->cem[0]](data->endpoints[0][1], data->endpoints[0][5], data->weights[i][ps[1]]);
                uint_fast8_t b =
                  FuncTableC[data->cem[0]](data->endpoints[0][2], data->endpoints[0][6], data->weights[i][ps[2]]);
                uint_fast8_t a =
                  FuncTableA[data->cem[0]](data->endpoints[0][3], data->endpoints[0][7], data->weights[i][ps[3]]);
                outbuf[i] = color(r, g, b, a);
            }
        }
    } else if (data->part_num > 1) {
        for (int i = 0; i < data->bw * data->bh; i++) {
            int p = data->partition[i];
            uint_fast8_t r =
              FuncTableC[data->cem[p]](data->endpoints[p][0], data->endpoints[p][4], data->weights[i][0]);
            uint_fast8_t g =
              FuncTableC[data->cem[p]](data->endpoints[p][1], data->endpoints[p][5], data->weights[i][0]);
            uint_fast8_t b =
              FuncTableC[data->cem[p]](data->endpoints[p][2], data->endpoints[p][6], data->weights[i][0]);
            uint_fast8_t a =
              FuncTableA[data->cem[p]](data->endpoints[p][3], data->endpoints[p][7], data->weights[i][0]);
            outbuf[i] = color(r, g, b, a);
        }
    } else {
        for (int i = 0; i < data->bw * data->bh; i++) {
            uint_fast8_t r =
              FuncTableC[data->cem[0]](data->endpoints[0][0], data->endpoints[0][4], data->weights[i][0]);
            uint_fast8_t g =
              FuncTableC[data->cem[0]](data->endpoints[0][1], data->endpoints[0][5], data->weights[i][0]);
            uint_fast8_t b =
              FuncTableC[data->cem[0]](data->endpoints[0][2], data->endpoints[0][6], data->weights[i][0]);
            uint_fast8_t a =
              FuncTableA[data->cem[0]](data->endpoints[0][3], data->endpoints[0][7], data->weights[i][0]);
            outbuf[i] = color(r, g, b, a);
        }
    }
}

void decode_block(const uint8_t *buf, const int bw, const int bh, uint32_t *outbuf) {
    if (buf[0] == 0xfc && (buf[1] & 1) == 1) {
        // void-extent
        uint_fast32_t c;
        if (buf[1] & 2)
            c = color(f16ptr_to_u8(buf + 8), f16ptr_to_u8(buf + 10), f16ptr_to_u8(buf + 12), f16ptr_to_u8(buf + 14));
        else
            c = color(buf[9], buf[11], buf[13], buf[15]);
        for (int i = 0; i < bw * bh; i++)
            outbuf[i] = c;
    } else if (((buf[0] & 0xc3) == 0xc0 && (buf[1] & 1) == 1) || (buf[0] & 0xf) == 0) {
        // reserved (illegal)
        uint_fast32_t c = color(255, 0, 255, 255);
        for (int i = 0; i < bw * bh; i++)
            outbuf[i] = c;
    } else {
        BlockData block_data;
        block_data.bw = bw;
        block_data.bh = bh;
        decode_block_params(buf, &block_data);
        decode_endpoints(buf, &block_data);
        decode_weights(buf, &block_data);
        if (block_data.part_num > 1)
            select_partition(buf, &block_data);
        applicate_color(&block_data, outbuf);
    }
}

int decode_astc(const uint8_t *data, const long w, const long h, const int bw, const int bh, uint32_t *image) {
    const long num_blocks_x = (w + bw - 1) / bw;
    const long num_blocks_y = (h + bh - 1) / bh;
    uint32_t buffer[144];
    const uint8_t *d = data;
    for (long by = 0; by < num_blocks_y; by++) {
        for (long bx = 0; bx < num_blocks_x; bx++, d += 16) {
            decode_block(d, bw, bh, buffer);
            copy_block_buffer(bx, by, w, h, bw, bh, buffer, image);
        }
    }
    return 1;
}