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196 lines
5.0 KiB
196 lines
5.0 KiB
// +build !appengine
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// +build gc
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// +build !noasm
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#include "textflag.h"
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#include "funcdata.h"
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#include "go_asm.h"
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#ifdef GOAMD64_v4
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#ifndef GOAMD64_v3
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#define GOAMD64_v3
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#endif
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#endif
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#define bufoff 256 // see decompress.go, we're using [4][256]byte table
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//func decompress4x_main_loop_x86(pbr0, pbr1, pbr2, pbr3 *bitReaderShifted,
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// peekBits uint8, buf *byte, tbl *dEntrySingle) (int, bool)
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TEXT ·decompress4x_main_loop_x86(SB), NOSPLIT, $8
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#define off R8
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#define buffer DI
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#define table SI
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#define br_bits_read R9
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#define br_value R10
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#define br_offset R11
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#define peek_bits R12
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#define exhausted DX
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#define br0 R13
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#define br1 R14
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#define br2 R15
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#define br3 BP
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MOVQ BP, 0(SP)
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XORQ exhausted, exhausted // exhausted = false
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XORQ off, off // off = 0
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MOVBQZX peekBits+32(FP), peek_bits
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MOVQ buf+40(FP), buffer
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MOVQ tbl+48(FP), table
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MOVQ pbr0+0(FP), br0
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MOVQ pbr1+8(FP), br1
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MOVQ pbr2+16(FP), br2
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MOVQ pbr3+24(FP), br3
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main_loop:
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{{ define "decode_2_values_x86" }}
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// const stream = {{ var "id" }}
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// br{{ var "id"}}.fillFast()
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MOVBQZX bitReaderShifted_bitsRead(br{{ var "id" }}), br_bits_read
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MOVQ bitReaderShifted_value(br{{ var "id" }}), br_value
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MOVQ bitReaderShifted_off(br{{ var "id" }}), br_offset
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// We must have at least 2 * max tablelog left
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CMPQ br_bits_read, $64-22
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JBE skip_fill{{ var "id" }}
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SUBQ $32, br_bits_read // b.bitsRead -= 32
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SUBQ $4, br_offset // b.off -= 4
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// v := b.in[b.off-4 : b.off]
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// v = v[:4]
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// low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
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MOVQ bitReaderShifted_in(br{{ var "id" }}), AX
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// b.value |= uint64(low) << (b.bitsRead & 63)
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#ifdef GOAMD64_v3
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SHLXQ br_bits_read, 0(br_offset)(AX*1), AX // AX = uint32(b.in[b.off:b.off+4]) << (b.bitsRead & 63)
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#else
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MOVL 0(br_offset)(AX*1), AX // AX = uint32(b.in[b.off:b.off+4])
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MOVQ br_bits_read, CX
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SHLQ CL, AX
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#endif
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ORQ AX, br_value
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// exhausted = exhausted || (br{{ var "id"}}.off < 4)
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CMPQ br_offset, $4
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SETLT DL
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ORB DL, DH
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// }
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skip_fill{{ var "id" }}:
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// val0 := br{{ var "id"}}.peekTopBits(peekBits)
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#ifdef GOAMD64_v3
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SHRXQ peek_bits, br_value, AX // AX = (value >> peek_bits) & mask
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#else
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MOVQ br_value, AX
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MOVQ peek_bits, CX
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SHRQ CL, AX // AX = (value >> peek_bits) & mask
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#endif
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// v0 := table[val0&mask]
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MOVW 0(table)(AX*2), AX // AX - v0
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// br{{ var "id"}}.advance(uint8(v0.entry))
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MOVB AH, BL // BL = uint8(v0.entry >> 8)
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#ifdef GOAMD64_v3
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MOVBQZX AL, CX
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SHLXQ AX, br_value, br_value // value <<= n
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#else
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MOVBQZX AL, CX
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SHLQ CL, br_value // value <<= n
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#endif
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ADDQ CX, br_bits_read // bits_read += n
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#ifdef GOAMD64_v3
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SHRXQ peek_bits, br_value, AX // AX = (value >> peek_bits) & mask
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#else
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// val1 := br{{ var "id"}}.peekTopBits(peekBits)
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MOVQ peek_bits, CX
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MOVQ br_value, AX
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SHRQ CL, AX // AX = (value >> peek_bits) & mask
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#endif
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// v1 := table[val1&mask]
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MOVW 0(table)(AX*2), AX // AX - v1
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// br{{ var "id"}}.advance(uint8(v1.entry))
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MOVB AH, BH // BH = uint8(v1.entry >> 8)
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#ifdef GOAMD64_v3
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MOVBQZX AL, CX
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SHLXQ AX, br_value, br_value // value <<= n
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#else
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MOVBQZX AL, CX
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SHLQ CL, br_value // value <<= n
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#endif
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ADDQ CX, br_bits_read // bits_read += n
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// these two writes get coalesced
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// buf[stream][off] = uint8(v0.entry >> 8)
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// buf[stream][off+1] = uint8(v1.entry >> 8)
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MOVW BX, {{ var "bufofs" }}(buffer)(off*1)
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// update the bitrader reader structure
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MOVB br_bits_read, bitReaderShifted_bitsRead(br{{ var "id" }})
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MOVQ br_value, bitReaderShifted_value(br{{ var "id" }})
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MOVQ br_offset, bitReaderShifted_off(br{{ var "id" }})
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{{ end }}
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{{ set "id" "0" }}
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{{ set "ofs" "0" }}
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{{ set "bufofs" "0" }} {{/* id * bufoff */}}
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{{ template "decode_2_values_x86" . }}
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{{ set "id" "1" }}
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{{ set "ofs" "8" }}
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{{ set "bufofs" "256" }}
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{{ template "decode_2_values_x86" . }}
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{{ set "id" "2" }}
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{{ set "ofs" "16" }}
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{{ set "bufofs" "512" }}
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{{ template "decode_2_values_x86" . }}
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{{ set "id" "3" }}
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{{ set "ofs" "24" }}
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{{ set "bufofs" "768" }}
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{{ template "decode_2_values_x86" . }}
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ADDQ $2, off // off += 2
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TESTB DH, DH // any br[i].ofs < 4?
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JNZ end
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CMPQ off, $bufoff
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JL main_loop
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end:
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MOVQ 0(SP), BP
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MOVB off, ret+56(FP)
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RET
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#undef off
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#undef buffer
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#undef table
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#undef br_bits_read
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#undef br_value
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#undef br_offset
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#undef peek_bits
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#undef exhausted
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#undef br0
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#undef br1
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#undef br2
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#undef br3
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