aiops/backend/pkg/rdp/rle/bpp2.go

package rle

import (
	"fmt"
	"unsafe"
)

func decompress2(output *[]uint8, width, height int, input []uint8, size int) bool {
	needed := width * height

	var out []uint16
	if v := decompress2Pool.Get(); v != nil {
		out = v.([]uint16)
		if cap(out) < needed {
			out = make([]uint16, needed)
		} else {
			out = out[:needed]
		}
	} else {
		out = make([]uint16, needed)
	}
	defer func() { decompress2Pool.Put(out[:cap(out)]) }()

	var (
		prevline, line, count            int
		offset, code                     int
		x                                int = width
		opcode                           int
		lastopcode                       int = -1
		insertmix, bicolour, isfillormix bool
		mixmask, mask                    uint8
		colour1, colour2                 uint16
		mix                              uint16 = 0xffff
		fom_mask                         uint8
	)

	for len(input) != 0 {
		fom_mask = 0
		code = CVAL(&input)
		opcode = code >> 4
		/* Handle different opcode forms */
		switch opcode {
		case 0xc, 0xd, 0xe:
			opcode -= 6
			count = code & 0xf
			offset = 16
			break
		case 0xf:
			opcode = code & 0xf
			if opcode < 9 {
				count = CVAL(&input)
				count |= CVAL(&input) << 8
			} else {
				count = 1
				if opcode < 0xb {
					count = 8
				}
			}
			offset = 0
			break
		default:
			opcode >>= 1
			count = code & 0x1f
			offset = 32
			break
		}

		/* Handle strange cases for counts */
		if offset != 0 {
			isfillormix = ((opcode == 2) || (opcode == 7))
			if count == 0 {
				if isfillormix {
					count = CVAL(&input) + 1
				} else {
					count = CVAL(&input) + offset
				}
			} else if isfillormix {
				count <<= 3
			}
		}
		/* Read preliminary data */
		switch opcode {
		case 0: /* Fill */
			if (lastopcode == opcode) && !((x == width) && (prevline == 0)) {
				insertmix = true
			}
			break
		case 8: /* Bicolour */
			CVAL2(&input, &colour1)
			CVAL2(&input, &colour2)
			break
		case 3: /* Colour */
			CVAL2(&input, &colour2)
			break
		case 6: /* SetMix/Mix */
			fallthrough
		case 7: /* SetMix/FillOrMix */
			CVAL2(&input, &mix)
			opcode -= 5
			break
		case 9: /* FillOrMix_1 */
			mask = 0x03
			opcode = 0x02
			fom_mask = 3
			break
		case 0x0a: /* FillOrMix_2 */
			mask = 0x05
			opcode = 0x02
			fom_mask = 5
			break
		}
		lastopcode = opcode
		mixmask = 0
		/* Output body */
		for count > 0 {
			if x >= width {
				if height <= 0 {
					return false
				}

				x = 0
				height--
				prevline = line
				line = height * width
			}
			switch opcode {
			case 0: /* Fill */
				if insertmix {
					if prevline == 0 {
						out[x+line] = mix
					} else {
						out[x+line] = out[prevline+x] ^ mix
					}
					insertmix = false
					count--
					x++
				}
				n := min(count, width-x)
				if prevline == 0 {
					clear(out[x+line : x+line+n])
				} else {
					copy(out[x+line:x+line+n], out[prevline+x:prevline+x+n])
				}
				count -= n
				x += n
				break
			case 1: /* Mix */
				n := min(count, width-x)
				if prevline == 0 {
					seg := out[x+line : x+line+n]
					for i := range seg {
						seg[i] = mix
					}
				} else {
					src := out[prevline+x : prevline+x+n]
					dst := out[x+line : x+line+n]
					for i := range dst {
						dst[i] = src[i] ^ mix
					}
				}
				count -= n
				x += n
				break
			case 2: /* Fill or Mix */
				if prevline == 0 {
					for count > 0 && x < width {
						mixmask <<= 1
						if mixmask == 0 {
							mask = fom_mask
							if fom_mask == 0 {
								mask = uint8(CVAL(&input))
								mixmask = 1
							}
						}
						if mask&mixmask != 0 {
							out[x+line] = mix
						} else {
							out[x+line] = 0
						}
					
						count--
						x++
					}
				} else {
					for count > 0 && x < width {
						mixmask = mixmask << 1
						if mixmask == 0 {
							mask = fom_mask
							if fom_mask == 0 {
								mask = uint8(CVAL(&input))
								mixmask = 1
							}
						}
						if mask&mixmask != 0 {
							out[x+line] = out[prevline+x] ^ mix
						} else {
							out[x+line] = out[prevline+x]
						}
					
						count--
						x++
					}
				}
				break
			case 3: /* Colour */
				n := min(count, width-x)
				seg := out[x+line : x+line+n]
				for i := range seg {
					seg[i] = colour2
				}
				count -= n
				x += n
				break
			case 4: /* Copy */
				for count > 0 && x < width {
					n := min(count, width-x)
					if len(input) < n*2 {
						return false
					}
					copy(out[x+line:x+line+n], unsafe.Slice((*uint16)(unsafe.Pointer(&input[0])), n))
					input = input[n*2:]
					count -= n
					x += n
				}

				break
			case 8: /* Bicolour */
				for count > 0 && x < width {
					if bicolour {
						out[x+line] = colour2
						bicolour = false
					} else {
						out[x+line] = colour1
						bicolour = true
						count++
					}
				
					count--
					x++
				}

				break
			case 0xd: /* White */
				n2 := min(count, width-x)
				seg2 := out[x+line : x+line+n2]
				for i := range seg2 {
					seg2[i] = 0xffff
				}
				count -= n2
				x += n2
				break
			case 0xe: /* Black */
				n3 := min(count, width-x)
				clear(out[x+line : x+line+n3])
				count -= n3
				x += n3
				break
			default:
				fmt.Printf("bitmap opcode 0x%x\n", opcode)
				return false
			}
		}
	}
	outBytes := *output
	for i, v := range out {
		outBytes[i*2] = byte(v >> 8)
		outBytes[i*2+1] = byte(v)
	}
	return true
}

// /* 3 byte bitmap decompress */