gtsocial-umbx

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int.go (3977B)

      1 package encoder
      2 
      3 import (
      4 	"unsafe"
      5 )
      6 
      7 var endianness int
      8 
      9 func init() {
     10 	var b [2]byte
     11 	*(*uint16)(unsafe.Pointer(&b)) = uint16(0xABCD)
     12 
     13 	switch b[0] {
     14 	case 0xCD:
     15 		endianness = 0 // LE
     16 	case 0xAB:
     17 		endianness = 1 // BE
     18 	default:
     19 		panic("could not determine endianness")
     20 	}
     21 }
     22 
     23 // "00010203...96979899" cast to []uint16
     24 var intLELookup = [100]uint16{
     25 	0x3030, 0x3130, 0x3230, 0x3330, 0x3430, 0x3530, 0x3630, 0x3730, 0x3830, 0x3930,
     26 	0x3031, 0x3131, 0x3231, 0x3331, 0x3431, 0x3531, 0x3631, 0x3731, 0x3831, 0x3931,
     27 	0x3032, 0x3132, 0x3232, 0x3332, 0x3432, 0x3532, 0x3632, 0x3732, 0x3832, 0x3932,
     28 	0x3033, 0x3133, 0x3233, 0x3333, 0x3433, 0x3533, 0x3633, 0x3733, 0x3833, 0x3933,
     29 	0x3034, 0x3134, 0x3234, 0x3334, 0x3434, 0x3534, 0x3634, 0x3734, 0x3834, 0x3934,
     30 	0x3035, 0x3135, 0x3235, 0x3335, 0x3435, 0x3535, 0x3635, 0x3735, 0x3835, 0x3935,
     31 	0x3036, 0x3136, 0x3236, 0x3336, 0x3436, 0x3536, 0x3636, 0x3736, 0x3836, 0x3936,
     32 	0x3037, 0x3137, 0x3237, 0x3337, 0x3437, 0x3537, 0x3637, 0x3737, 0x3837, 0x3937,
     33 	0x3038, 0x3138, 0x3238, 0x3338, 0x3438, 0x3538, 0x3638, 0x3738, 0x3838, 0x3938,
     34 	0x3039, 0x3139, 0x3239, 0x3339, 0x3439, 0x3539, 0x3639, 0x3739, 0x3839, 0x3939,
     35 }
     36 
     37 var intBELookup = [100]uint16{
     38 	0x3030, 0x3031, 0x3032, 0x3033, 0x3034, 0x3035, 0x3036, 0x3037, 0x3038, 0x3039,
     39 	0x3130, 0x3131, 0x3132, 0x3133, 0x3134, 0x3135, 0x3136, 0x3137, 0x3138, 0x3139,
     40 	0x3230, 0x3231, 0x3232, 0x3233, 0x3234, 0x3235, 0x3236, 0x3237, 0x3238, 0x3239,
     41 	0x3330, 0x3331, 0x3332, 0x3333, 0x3334, 0x3335, 0x3336, 0x3337, 0x3338, 0x3339,
     42 	0x3430, 0x3431, 0x3432, 0x3433, 0x3434, 0x3435, 0x3436, 0x3437, 0x3438, 0x3439,
     43 	0x3530, 0x3531, 0x3532, 0x3533, 0x3534, 0x3535, 0x3536, 0x3537, 0x3538, 0x3539,
     44 	0x3630, 0x3631, 0x3632, 0x3633, 0x3634, 0x3635, 0x3636, 0x3637, 0x3638, 0x3639,
     45 	0x3730, 0x3731, 0x3732, 0x3733, 0x3734, 0x3735, 0x3736, 0x3737, 0x3738, 0x3739,
     46 	0x3830, 0x3831, 0x3832, 0x3833, 0x3834, 0x3835, 0x3836, 0x3837, 0x3838, 0x3839,
     47 	0x3930, 0x3931, 0x3932, 0x3933, 0x3934, 0x3935, 0x3936, 0x3937, 0x3938, 0x3939,
     48 }
     49 
     50 var intLookup = [2]*[100]uint16{&intLELookup, &intBELookup}
     51 
     52 func numMask(numBitSize uint8) uint64 {
     53 	return 1<<numBitSize - 1
     54 }
     55 
     56 func AppendInt(_ *RuntimeContext, out []byte, p uintptr, code *Opcode) []byte {
     57 	var u64 uint64
     58 	switch code.NumBitSize {
     59 	case 8:
     60 		u64 = (uint64)(**(**uint8)(unsafe.Pointer(&p)))
     61 	case 16:
     62 		u64 = (uint64)(**(**uint16)(unsafe.Pointer(&p)))
     63 	case 32:
     64 		u64 = (uint64)(**(**uint32)(unsafe.Pointer(&p)))
     65 	case 64:
     66 		u64 = **(**uint64)(unsafe.Pointer(&p))
     67 	}
     68 	mask := numMask(code.NumBitSize)
     69 	n := u64 & mask
     70 	negative := (u64>>(code.NumBitSize-1))&1 == 1
     71 	if !negative {
     72 		if n < 10 {
     73 			return append(out, byte(n+'0'))
     74 		} else if n < 100 {
     75 			u := intLELookup[n]
     76 			return append(out, byte(u), byte(u>>8))
     77 		}
     78 	} else {
     79 		n = -n & mask
     80 	}
     81 
     82 	lookup := intLookup[endianness]
     83 
     84 	var b [22]byte
     85 	u := (*[11]uint16)(unsafe.Pointer(&b))
     86 	i := 11
     87 
     88 	for n >= 100 {
     89 		j := n % 100
     90 		n /= 100
     91 		i--
     92 		u[i] = lookup[j]
     93 	}
     94 
     95 	i--
     96 	u[i] = lookup[n]
     97 
     98 	i *= 2 // convert to byte index
     99 	if n < 10 {
    100 		i++ // remove leading zero
    101 	}
    102 	if negative {
    103 		i--
    104 		b[i] = '-'
    105 	}
    106 
    107 	return append(out, b[i:]...)
    108 }
    109 
    110 func AppendUint(_ *RuntimeContext, out []byte, p uintptr, code *Opcode) []byte {
    111 	var u64 uint64
    112 	switch code.NumBitSize {
    113 	case 8:
    114 		u64 = (uint64)(**(**uint8)(unsafe.Pointer(&p)))
    115 	case 16:
    116 		u64 = (uint64)(**(**uint16)(unsafe.Pointer(&p)))
    117 	case 32:
    118 		u64 = (uint64)(**(**uint32)(unsafe.Pointer(&p)))
    119 	case 64:
    120 		u64 = **(**uint64)(unsafe.Pointer(&p))
    121 	}
    122 	mask := numMask(code.NumBitSize)
    123 	n := u64 & mask
    124 	if n < 10 {
    125 		return append(out, byte(n+'0'))
    126 	} else if n < 100 {
    127 		u := intLELookup[n]
    128 		return append(out, byte(u), byte(u>>8))
    129 	}
    130 
    131 	lookup := intLookup[endianness]
    132 
    133 	var b [22]byte
    134 	u := (*[11]uint16)(unsafe.Pointer(&b))
    135 	i := 11
    136 
    137 	for n >= 100 {
    138 		j := n % 100
    139 		n /= 100
    140 		i--
    141 		u[i] = lookup[j]
    142 	}
    143 
    144 	i--
    145 	u[i] = lookup[n]
    146 
    147 	i *= 2 // convert to byte index
    148 	if n < 10 {
    149 		i++ // remove leading zero
    150 	}
    151 	return append(out, b[i:]...)
    152 }