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This commit is contained in:
Eric MacDonald
2021-09-08 22:05:57 -04:00
parent 710066f228
commit fddcbf7e7a
1 changed files with 25 additions and 23 deletions
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48
zefie_wtvp_minisrv/WTVLzpf.js
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@@ -20,8 +20,8 @@
class WTVLzpf { class WTVLzpf {
// Note: currentlty doesn't offer optimal streaming support but this is good enough to meet perf demands at the scale we're at. // Note: currentlty doesn't offer optimal streaming support but this is good enough to meet perf demands at the scale we're at.
current_length = 0; current_bit_length = 0;
current_literal = 0; current_bits = 0;
ring_bufer_index = 0xFFFF; ring_bufer_index = 0xFFFF;
working_data = 0; working_data = 0;
match_index = 0; match_index = 0;
@@ -316,8 +316,8 @@ class WTVLzpf {
* @returns {undefined} * @returns {undefined}
*/ */
clear() { clear() {
this.current_length = 0; this.current_bit_length = 0;
this.current_literal = 0; this.current_bits = 0;
this.ring_bufer_index = 0xFFFF; this.ring_bufer_index = 0xFFFF;
this.working_data = 0; this.working_data = 0;
this.match_index = 0; this.match_index = 0;
@@ -341,22 +341,24 @@ class WTVLzpf {
} }
/** /**
* Encodes a literal onto the compressed byte array. * Add bits onto the compressed bit stream.
* *
* @param code_length {Number} bit length of the code * When we reach 8 bits we push a byte onto the compressed byte array.
* @param code {Number} code to be encoded *
* @param bits {Number} bits to add
* @param bit_length {Number} bit length
* *
* @returns {undefined} * @returns {undefined}
*/ */
EncodeLiteral(code_length, code) { AddBits(bits, bit_length) {
this.current_literal |= code >>> (this.current_length & 0x1F); this.current_bits |= code >>> (this.current_bit_length & 0x1F);
this.current_length += code_length; this.current_bit_length += code_length;
while (this.current_length > 7) { while (this.current_bit_length > 7) {
this.AddByte((this.current_literal >>> 0x18) & 0xFF); this.AddByte((this.current_bits >>> 0x18) & 0xFF);
this.current_length -= 8; this.current_bit_length -= 8;
this.current_literal = (this.current_literal << 8) & 0xFFFFFFFF; this.current_bits = (this.current_bits << 8) & 0xFFFFFFFF;
} }
} }
@@ -432,7 +434,7 @@ class WTVLzpf {
} }
if (code_length > 0) { if (code_length > 0) {
this.EncodeLiteral(code_length, code); this.AddBits(code, code_length);
} }
} }
} }
@@ -449,32 +451,32 @@ class WTVLzpf {
var code = -1; var code = -1;
if (this.type_index == 2) { if (this.type_index == 2) {
this.EncodeLiteral(0x10, 0x00990000); this.AddBits(0x00990000, 0x10);
} else if (this.type_index >= 3) { } else if (this.type_index >= 3) {
if (this.type_index == 4) { if (this.type_index == 4) {
code_length = this.matchEncode[this.match_index][1]; code_length = this.matchEncode[this.match_index][1];
code = this.matchEncode[this.match_index][0]; code = this.matchEncode[this.match_index][0];
this.EncodeLiteral(code_length, code); this.AddBits(code, code_length);
} }
var hash_index = (this.working_data >>> 0x0B ^ this.working_data) & 0x0FFF; var hash_index = (this.working_data >>> 0x0B ^ this.working_data) & 0x0FFF;
var ring_bufer_index = this.hash_table[hash_index]; var ring_bufer_index = this.hash_table[hash_index];
if (ring_bufer_index == 0xFFFF) { if (ring_bufer_index == 0xFFFF) {
this.EncodeLiteral(0x10, 0x00990000); this.AddBits(0x00990000, 0x10);
} else { } else {
this.EncodeLiteral(0x11, 0x004c8000); this.AddBits(0x004C8000, 0x11);
} }
} }
// Below is just metadata. The compressed block is complete. // Below is just metadata. The compressed block is complete.
// Encode checksum // Encode checksum
this.EncodeLiteral(0x08, (this.checksum << 0x10) & 0xFFFFFFFF); this.AddBits((this.checksum << 0x10) & 0xFFFFFFFF, 0x08);
this.EncodeLiteral(0x08, (this.checksum << 0x18) & 0xFFFFFFFF); this.AddBits((this.checksum << 0x18) & 0xFFFFFFFF, 0x08);
// End // End
if (this.current_literal != 0x00) { if (this.current_bits != 0x00) {
this.AddByte((this.current_literal >>> 0x18) & 0xFF); this.AddByte((this.current_bits >>> 0x18) & 0xFF);
} }
this.AddByte(this.filler_byte); this.AddByte(this.filler_byte);