Add elf parser
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3
Makefile
3
Makefile
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@ -76,7 +76,8 @@ TRANSPILE_ES6_FLAGS=\
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CORE_FILES=src/const.js src/io.js src/main.js src/lib.js src/fpu.js src/ide.js src/pci.js src/floppy.js src/memory.js\
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src/dma.js src/pit.js src/vga.js src/ps2.js src/pic.js src/rtc.js src/uart.js src/hpet.js src/acpi.js src/apic.js\
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src/state.js src/ne2k.js src/virtio.js src/bus.js src/log.js src/config.js\
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src/cpu.js src/translate.js src/modrm.js src/string.js src/arith.js src/misc_instr.js src/instructions.js src/debug.js
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src/cpu.js src/translate.js src/modrm.js src/string.js src/arith.js src/misc_instr.js src/instructions.js src/debug.js \
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src/elf.js
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LIB_FILES=lib/9p.js lib/filesystem.js lib/jor1k.js lib/marshall.js lib/utf8.js
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BROWSER_FILES=src/browser/screen.js\
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src/browser/keyboard.js src/browser/mouse.js src/browser/serial.js\
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@ -6,7 +6,7 @@
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"const.js config.js log.js cpu.js debug.js translate.js modrm.js string.js arith.js misc_instr.js instructions.js " +
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"io.js main.js lib.js ide.js fpu.js pci.js floppy.js " +
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"memory.js dma.js pit.js vga.js ps2.js pic.js rtc.js uart.js acpi.js apic.js hpet.js " +
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"ne2k.js state.js virtio.js bus.js";
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"ne2k.js state.js virtio.js bus.js elf.js";
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var BROWSER_FILES = "main.js screen.js keyboard.js mouse.js serial.js lib.js network.js starter.js worker_bus.js";
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//var LIB_FILES = "esprima.js walk.js";
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222
src/elf.js
Normal file
222
src/elf.js
Normal file
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@ -0,0 +1,222 @@
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"use strict";
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// A minimal elf parser for loading 32 bit, x86, little endian, executable elf files
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const ELF_MAGIC = 0x464C457F;
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let types = DataView.prototype;
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let U8 = { size: 1, get: types.getUint8, set: types.setUint8, };
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let U16 = { size: 2, get: types.getUint16, set: types.setUint16, };
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let U32 = { size: 4, get: types.getUint32, set: types.setUint32, };
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let pad = function(size)
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{
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return {
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size,
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get: offset => -1,
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};
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}
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let Header = create_struct([
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{ magic: U32, },
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{ class: U8, },
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{ data: U8, },
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{ version0: U8, },
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{ osabi: U8, },
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{ abiversion: U8, },
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{ pad0: pad(7) },
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{ type: U16, },
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{ machine: U16, },
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{ version1: U32, },
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{ entry: U32, },
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{ phoff: U32, },
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{ shoff: U32, },
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{ flags: U32, },
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{ ehsize: U16, },
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{ phentsize: U16, },
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{ phnum: U16, },
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{ shentsize: U16, },
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{ shnum: U16, },
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{ shstrndx: U16, },
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]);
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console.assert(Header.reduce((a, entry) => a + entry.size, 0) === 52);
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let ProgramHeader = create_struct([
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{ type: U32, },
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{ offset: U32, },
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{ vaddr: U32, },
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{ paddr: U32, },
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{ filesz: U32, },
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{ memsz: U32, },
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{ flags: U32, },
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{ align: U32, },
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]);
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console.assert(ProgramHeader.reduce((a, entry) => a + entry.size, 0) === 32);
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let SectionHeader = create_struct([
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{ name: U32, },
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{ type: U32, },
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{ flags: U32, },
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{ addr: U32, },
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{ offset: U32, },
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{ size: U32, },
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{ link: U32, },
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{ info: U32, },
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{ addralign: U32, },
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{ entsize: U32, },
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]);
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console.assert(SectionHeader.reduce((a, entry) => a + entry.size, 0) === 40);
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// From [{ name: type }, ...] to [{ name, type, size, get, set }, ...]
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function create_struct(struct)
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{
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return struct.map(function(entry)
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{
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let keys = Object.keys(entry);
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console.assert(keys.length === 1);
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let name = keys[0];
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let type = entry[name];
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console.assert(type.size > 0);
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return {
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name,
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type,
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size: type.size,
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get: type.get,
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set: type.set,
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};
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});
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}
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/** @param {ArrayBuffer} buffer */
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function read_elf(buffer)
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{
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let view = new DataView(buffer);
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let [header, offset] = read_struct(view, Header);
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console.assert(offset === 52);
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if(DEBUG)
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{
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for(let key in header)
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{
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console.log(key + ": 0x" + header[key].toString(16));
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}
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console.log(header);
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}
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console.assert(header.magic === ELF_MAGIC, "Bad magic");
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console.assert(header.class === 1, "Unimplemented: 64 bit elf");
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console.assert(header.data === 1, "Unimplemented: big endian");
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console.assert(header.version0 === 1, "Bad version0");
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// 1, 2, 3, 4 specify whether the object is relocatable, executable,
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// shared, or core, respectively.
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console.assert(header.type === 2, "Unimplemented type");
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console.assert(header.version1 === 1, "Bad version1");
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// these are different in 64 bit
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console.assert(header.ehsize === 52, "Bad header size");
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console.assert(header.phentsize === 32, "Bad program header size");
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console.assert(header.shentsize === 40, "Bad section header size");
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let [program_headers, ph_offset] = read_structs(
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view_slice(view, header.phoff, header.phentsize * header.phnum),
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ProgramHeader,
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header.phnum);
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let [sections_headers, sh_offset] = read_structs(
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view_slice(view, header.shoff, header.shentsize * header.shnum),
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SectionHeader,
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header.shnum);
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if(DEBUG)
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{
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console.log("%d program headers:", program_headers.length);
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for(let program of program_headers)
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{
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console.log(
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"type=%s offset=%s vaddr=%s paddr=%s " +
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"filesz=%s memsz=%s flags=%s align=%s",
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program.type.toString(16),
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program.offset.toString(16),
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program.vaddr.toString(16),
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program.paddr.toString(16),
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program.filesz.toString(16),
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program.memsz.toString(16),
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program.flags.toString(16),
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program.align.toString(16)
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);
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}
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console.log("%d program headers:", sections_headers.length);
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for(let section of sections_headers)
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{
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console.log(
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"name=%s type=%s flags=%s addr=%s offset=%s " +
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"size=%s link=%s info=%s addralign=%s entsize=%s",
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section.name.toString(16),
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section.type.toString(16),
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section.flags.toString(16),
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section.addr.toString(16),
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section.offset.toString(16),
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section.size.toString(16),
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section.link.toString(16),
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section.info.toString(16),
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section.addralign.toString(16),
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section.entsize.toString(16)
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);
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}
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}
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return {
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header,
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program_headers,
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sections_headers,
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};
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}
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function read_struct(view, Struct)
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{
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let result = {};
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let offset = 0;
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const LITTLE_ENDIAN = true; // big endian not supported yet
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for(let entry of Struct)
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{
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let value = entry.get.call(view, offset, LITTLE_ENDIAN);
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console.assert(result[entry.name] === undefined);
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result[entry.name] = value;
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offset += entry.size;
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}
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return [result, offset];
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}
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function read_structs(view, Struct, count)
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{
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let result = [];
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let offset = 0;
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for(var i = 0; i < count; i++)
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{
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let [s, size] = read_struct(view_slice(view, offset), Struct);
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result.push(s);
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offset += size;
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}
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return [result, offset];
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}
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/** @param {number=} length */
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function view_slice(view, offset, length)
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{
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return new DataView(view.buffer, view.byteOffset + offset, length);
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}
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