#include <my_global.h>
#include <string.h>
#include <stdint.h>
#include <stddef.h>

typedef unsigned (*my_crc32_t)(unsigned, const void *, size_t);

#ifdef HAVE_ARMV8_CRC

# ifdef HAVE_ARMV8_CRYPTO
static unsigned crc32c_aarch64_pmull(unsigned, const void *, size_t);
# endif

# ifdef __APPLE__
#  include <sys/sysctl.h>

int crc32_aarch64_available(void)
{
  int ret;
  size_t len = sizeof(ret);
  if (sysctlbyname("hw.optional.armv8_crc32", &ret, &len, NULL, 0) == -1)
    return 0;
  return ret;
}

my_crc32_t crc32c_aarch64_available(void)
{
# ifdef HAVE_ARMV8_CRYPTO
  if (crc32_aarch64_available())
    return crc32c_aarch64_pmull;
# endif
  return NULL;
}
# else
#  include <sys/auxv.h>
#  ifdef __FreeBSD__
static unsigned long getauxval(unsigned int key)
{
  unsigned long val;
  if (elf_aux_info(key, (void *)&val, (int)sizeof(val) != 0))
    return 0ul;
  return val;
}
#  else
#   include <asm/hwcap.h>
#  endif

#  ifndef HWCAP_CRC32
#   define HWCAP_CRC32 (1 << 7)
#  endif

#  ifndef HWCAP_PMULL
#   define HWCAP_PMULL (1 << 4)
#  endif

/* ARM made crc32 default from ARMv8.1 but optional in ARMv8A
 * Runtime check API.
 */
int crc32_aarch64_available(void)
{
  unsigned long auxv= getauxval(AT_HWCAP);
  return (auxv & HWCAP_CRC32) != 0;
}
# endif

# ifndef __APPLE__
static unsigned crc32c_aarch64(unsigned, const void *, size_t);

my_crc32_t crc32c_aarch64_available(void)
{
  unsigned long auxv= getauxval(AT_HWCAP);
  if (!(auxv & HWCAP_CRC32))
    return NULL;
#  ifdef HAVE_ARMV8_CRYPTO
  /* Raspberry Pi 4 supports crc32 but doesn't support pmull (MDEV-23030). */
  if (auxv & HWCAP_PMULL)
    return crc32c_aarch64_pmull;
#  endif
  return crc32c_aarch64;
}
# endif

const char *crc32c_aarch64_impl(my_crc32_t c)
{
# ifdef HAVE_ARMV8_CRYPTO
  if (c == crc32c_aarch64_pmull)
    return "Using ARMv8 crc32 + pmull instructions";
# endif
# ifndef __APPLE__
  if (c == crc32c_aarch64)
    return "Using ARMv8 crc32 instructions";
# endif
  return NULL;
}
#endif /* HAVE_ARMV8_CRC */

#ifndef HAVE_ARMV8_CRC_CRYPTO_INTRINSICS

/* Request crc extension capabilities from the assembler */
asm(".arch_extension crc");

# ifdef HAVE_ARMV8_CRYPTO
/* crypto extension  */
asm(".arch_extension crypto");
# endif

#define CRC32CX(crc, value) __asm__("crc32cx %w[c], %w[c], %x[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32CW(crc, value) __asm__("crc32cw %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32CH(crc, value) __asm__("crc32ch %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32CB(crc, value) __asm__("crc32cb %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))

#define CRC32X(crc, value) __asm__("crc32x %w[c], %w[c], %x[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32W(crc, value) __asm__("crc32w %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32H(crc, value) __asm__("crc32h %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))
#define CRC32B(crc, value) __asm__("crc32b %w[c], %w[c], %w[v]":[c]"+r"(crc):[v]"r"(value))


#define CRC32C3X8(buffer, ITR) \
  __asm__("crc32cx %w[c1], %w[c1], %x[v]":[c1]"+r"(crc1):[v]"r"(*((const uint64_t *)buffer + 42*1 + (ITR))));\
  __asm__("crc32cx %w[c2], %w[c2], %x[v]":[c2]"+r"(crc2):[v]"r"(*((const uint64_t *)buffer + 42*2 + (ITR))));\
  __asm__("crc32cx %w[c0], %w[c0], %x[v]":[c0]"+r"(crc0):[v]"r"(*((const uint64_t *)buffer + 42*0 + (ITR))));

#else /* HAVE_ARMV8_CRC_CRYPTO_INTRINSICS  */

/* Intrinsics header*/
#include <arm_acle.h>
#include <arm_neon.h>

#define CRC32CX(crc, value) (crc) = __crc32cd((crc), (value))
#define CRC32CW(crc, value) (crc) = __crc32cw((crc), (value))
#define CRC32CH(crc, value) (crc) = __crc32ch((crc), (value))
#define CRC32CB(crc, value) (crc) = __crc32cb((crc), (value))

#define CRC32X(crc, value) (crc) = __crc32d((crc), (value))
#define CRC32W(crc, value) (crc) = __crc32w((crc), (value))
#define CRC32H(crc, value) (crc) = __crc32h((crc), (value))
#define CRC32B(crc, value) (crc) = __crc32b((crc), (value))

#define CRC32C3X8(buffer, ITR) \
  crc1 = __crc32cd(crc1, *((const uint64_t *)buffer + 42*1 + (ITR)));\
  crc2 = __crc32cd(crc2, *((const uint64_t *)buffer + 42*2 + (ITR)));\
  crc0 = __crc32cd(crc0, *((const uint64_t *)buffer + 42*0 + (ITR)));

#endif /* HAVE_ARMV8_CRC_CRYPTO_INTRINSICS */

#define CRC32C7X3X8(buffer, ITR) do {\
  CRC32C3X8(buffer, ((ITR) * 7 + 0)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 1)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 2)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 3)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 4)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 5)) \
  CRC32C3X8(buffer, ((ITR) * 7 + 6)) \
} while(0)

#define PREF4X64L1(buffer, PREF_OFFSET, ITR) \
  __asm__("PRFM PLDL1KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 0)*64));\
  __asm__("PRFM PLDL1KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 1)*64));\
  __asm__("PRFM PLDL1KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 2)*64));\
  __asm__("PRFM PLDL1KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 3)*64));

#define PREF1KL1(buffer, PREF_OFFSET) \
  PREF4X64L1(buffer,(PREF_OFFSET), 0) \
  PREF4X64L1(buffer,(PREF_OFFSET), 4) \
  PREF4X64L1(buffer,(PREF_OFFSET), 8) \
  PREF4X64L1(buffer,(PREF_OFFSET), 12)

#define PREF4X64L2(buffer, PREF_OFFSET, ITR) \
  __asm__("PRFM PLDL2KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 0)*64));\
  __asm__("PRFM PLDL2KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 1)*64));\
  __asm__("PRFM PLDL2KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 2)*64));\
  __asm__("PRFM PLDL2KEEP, [%x[v],%[c]]"::[v]"r"(buffer), [c]"I"((PREF_OFFSET) + ((ITR) + 3)*64));

#define PREF1KL2(buffer, PREF_OFFSET) \
  PREF4X64L2(buffer,(PREF_OFFSET), 0) \
  PREF4X64L2(buffer,(PREF_OFFSET), 4) \
  PREF4X64L2(buffer,(PREF_OFFSET), 8) \
  PREF4X64L2(buffer,(PREF_OFFSET), 12)

#ifndef __APPLE__
static unsigned crc32c_aarch64(unsigned crc, const void *buf, size_t len)
{
  int64_t length= (int64_t)len;
  const unsigned char *buffer= buf;

  crc^= 0xffffffff;

  while ((length-= sizeof(uint64_t)) >= 0)
  {
    CRC32CX(crc, *(uint64_t *)buffer);
    buffer+= sizeof(uint64_t);
  }

  /* The following is more efficient than the straight loop */
  if (length & sizeof(uint32_t))
  {
    CRC32CW(crc, *(uint32_t *)buffer);
    buffer+= sizeof(uint32_t);
  }

  if (length & sizeof(uint16_t))
  {
    CRC32CH(crc, *(uint16_t *)buffer);
    buffer+= sizeof(uint16_t);
  }

  if (length & sizeof(uint8_t))
    CRC32CB(crc, *buffer);

  return ~crc;
}
#endif

#ifdef HAVE_ARMV8_CRYPTO
static unsigned crc32c_aarch64_pmull(unsigned crc, const void *buf, size_t len)
{
  int64_t length= (int64_t)len;
  const unsigned char *buffer= buf;

  crc^= 0xffffffff;

  /* Crypto extension Support
   * Parallel computation with 1024 Bytes (per block)
   * Intrinsics Support
   */
# ifdef HAVE_ARMV8_CRC_CRYPTO_INTRINSICS
  /* Process per block size of 1024 Bytes
   * A block size = 8 + 42*3*sizeof(uint64_t) + 8
   */
  for (const poly64_t k1= 0xe417f38a, k2= 0x8f158014; (length-= 1024) >= 0; )
  {
    uint32_t crc0, crc1, crc2;
    uint64_t t0, t1;
    /* Prefetch 3*1024 data for avoiding L2 cache miss */
    PREF1KL2(buffer, 1024*3);
    /* Do first 8 bytes here for better pipelining */
    crc0= __crc32cd(crc, *(const uint64_t *)buffer);
    crc1= 0;
    crc2= 0;
    buffer+= sizeof(uint64_t);

    /* Process block inline
     * Process crc0 last to avoid dependency with above
     */
    CRC32C7X3X8(buffer, 0);
    CRC32C7X3X8(buffer, 1);
    CRC32C7X3X8(buffer, 2);
    CRC32C7X3X8(buffer, 3);
    CRC32C7X3X8(buffer, 4);
    CRC32C7X3X8(buffer, 5);

    buffer+= 42*3*sizeof(uint64_t);
    /* Prefetch data for following block to avoid L1 cache miss */
    PREF1KL1(buffer, 1024);

    /* Last 8 bytes
     * Merge crc0 and crc1 into crc2
     * crc1 multiply by K2
     * crc0 multiply by K1
     */
    t1= (uint64_t)vmull_p64(crc1, k2);
    t0= (uint64_t)vmull_p64(crc0, k1);
    crc= __crc32cd(crc2, *(const uint64_t *)buffer);
    crc1= __crc32cd(0, t1);
    crc^= crc1;
    crc0= __crc32cd(0, t0);
    crc^= crc0;

    buffer+= sizeof(uint64_t);
  }

# else /* HAVE_ARMV8_CRC_CRYPTO_INTRINSICS */
  /*No intrinsics*/
  __asm__("mov    x16,            #0xf38a         \n\t"
          "movk   x16,            #0xe417, lsl 16 \n\t"
          "mov    v1.2d[0],       x16             \n\t"
          "mov    x16,            #0x8014         \n\t"
          "movk   x16,            #0x8f15, lsl 16 \n\t"
          "mov    v0.2d[0],       x16             \n\t"
          :::"x16");

  while ((length-= 1024) >= 0)
  {
    uint32_t crc0, crc1, crc2;

    PREF1KL2(buffer, 1024*3);
    __asm__("crc32cx %w[c0], %w[c], %x[v]\n\t"
            :[c0]"=r"(crc0):[c]"r"(crc), [v]"r"(*(const uint64_t *)buffer):);
    crc1= 0;
    crc2= 0;
    buffer+= sizeof(uint64_t);

    CRC32C7X3X8(buffer, 0);
    CRC32C7X3X8(buffer, 1);
    CRC32C7X3X8(buffer, 2);
    CRC32C7X3X8(buffer, 3);
    CRC32C7X3X8(buffer, 4);
    CRC32C7X3X8(buffer, 5);

    buffer+= 42*3*sizeof(uint64_t);
    PREF1KL1(buffer, 1024);
    __asm__("mov            v2.2d[0],       %x[c1]          \n\t"
            "pmull          v2.1q,          v2.1d,  v0.1d   \n\t"
            "mov            v3.2d[0],       %x[c0]          \n\t"
            "pmull          v3.1q,          v3.1d,  v1.1d   \n\t"
            "crc32cx        %w[c],          %w[c2], %x[v]   \n\t"
            "mov            %x[c1],         v2.2d[0]        \n\t"
            "crc32cx        %w[c1],         wzr,    %x[c1]  \n\t"
            "eor            %w[c],          %w[c],  %w[c1]  \n\t"
            "mov            %x[c0],         v3.2d[0]        \n\t"
            "crc32cx        %w[c0],         wzr,    %x[c0]  \n\t"
            "eor            %w[c],          %w[c],  %w[c0]  \n\t"
            :[c1]"+r"(crc1), [c0]"+r"(crc0), [c2]"+r"(crc2), [c]"+r"(crc)
            :[v]"r"(*((const uint64_t *)buffer)));
    buffer+= sizeof(uint64_t);
  }
# endif /* HAVE_ARMV8_CRC_CRYPTO_INTRINSICS */

  /* Done if Input data size is aligned with 1024  */
  length+= 1024;
  if (length)
  {
    while ((length-= sizeof(uint64_t)) >= 0)
    {
      CRC32CX(crc, *(uint64_t *)buffer);
      buffer+= sizeof(uint64_t);
    }

    /* The following is more efficient than the straight loop */
    if (length & sizeof(uint32_t))
    {
      CRC32CW(crc, *(uint32_t *)buffer);
      buffer+= sizeof(uint32_t);
    }

    if (length & sizeof(uint16_t))
    {
      CRC32CH(crc, *(uint16_t *)buffer);
      buffer+= sizeof(uint16_t);
    }

    if (length & sizeof(uint8_t))
      CRC32CB(crc, *buffer);
  }

  return ~crc;
}
#endif /* HAVE_ARMV8_CRYPTO */

/* There are multiple approaches to calculate crc.
Approach-1: Process 8 bytes then 4 bytes then 2 bytes and then 1 bytes
Approach-2: Process 8 bytes and remaining workload using 1 bytes
Apporach-3: Process 64 bytes at once by issuing 8 crc call and remaining
            using 8/1 combination.

Based on micro-benchmark testing we found that Approach-2 works best especially
given small chunk of variable data. */
unsigned int crc32_aarch64(unsigned int crc, const void *buf, size_t len)
{
  const uint8_t *buf1= buf;
  const uint64_t *buf8= (const uint64_t *) (((uintptr_t) buf + 7) & ~7);

  crc= ~crc;

  /* if start pointer is not 8 bytes aligned */
  while ((buf1 != (const uint8_t *) buf8) && len)
  {
    CRC32B(crc, *buf1++);
    len--;
  }

  for (; len >= 8; len-= 8)
    CRC32X(crc, *buf8++);

  buf1= (const uint8_t *) buf8;
  while (len--)
    CRC32B(crc, *buf1++);

  return ~crc;
}
