maintain aspect ratio when rendering images - mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

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author	Kartik K. Agaram <vc@akkartik.com>	2021-07-29 08:24:27 -0700
committer	Kartik K. Agaram <vc@akkartik.com>	2021-07-29 08:24:27 -0700
commit	e55d3f5814d0f243d9d6a51f05433c14f0939055 (patch)
tree	3da63846ece6e84599abd02c30a71e4068448148 /tools/regs.mu
parent	54765018beb8a9c0dde67de527dbfedefdecaed0 (diff)
download	mu-e55d3f5814d0f243d9d6a51f05433c14f0939055.tar.gz

maintain aspect ratio when rendering images

Diffstat (limited to 'tools/regs.mu')

0 files changed, 0 insertions, 0 deletions

//: Loading SubX programs from ELF binaries. //: This will allow us to run them natively on a Linux kernel. //: Based on https://github.com/kragen/stoneknifeforth/blob/702d2ebe1b/386.c :(before "End Main") assert(argc > 1); if (is_equal(argv[1], "run")) { // Outside of tests, traces must be explicitly requested. if (Trace_file.is_open()) Trace_stream = new trace_stream; trace(2, "run") << "=== Starting to run" << end(); if (argc <= 2) { raise << "Not enough arguments provided.\n" << die(); } reset(); cerr << std::hex; load_elf(argv[2], argc, argv); while (EIP < End_of_program) // weak final-gasp termination check run_one_instruction(); raise << "executed past end of the world: " << EIP << " vs " << End_of_program << '\n' << end(); return 1; } :(code) void load_elf(const string& filename, int argc, char* argv[]) { int fd = open(filename.c_str(), O_RDONLY); if (fd < 0) raise << filename.c_str() << ": open" << perr() << '\n' << die(); off_t size = lseek(fd, 0, SEEK_END); lseek(fd, 0, SEEK_SET); uint8_t* elf_contents = static_cast<uint8_t*>(malloc(size)); if (elf_contents == NULL) raise << "malloc(" << size << ')' << perr() << '\n' << die(); ssize_t read_size = read(fd, elf_contents, size); if (size != read_size) raise << "read → " << size << " (!= " << read_size << ')' << perr() << '\n' << die(); load_elf_contents(elf_contents, size, argc, argv); free(elf_contents); } void load_elf_contents(uint8_t* elf_contents, size_t size, int argc, char* argv[]) { uint8_t magic[5] = {0}; memcpy(magic, elf_contents, 4); if (memcmp(magic, "\177ELF", 4) != 0) raise << "Invalid ELF file; starts with \"" << magic << '"' << die(); if (elf_contents[4] != 1) raise << "Only 32-bit ELF files (4-byte words; virtual addresses up to 4GB) supported.\n" << die(); if (elf_contents[5] != 1) raise << "Only little-endian ELF files supported.\n" << die(); // unused: remaining 10 bytes of e_ident uint32_t e_machine_type = u32_in(&elf_contents[16]); if (e_machine_type != 0x00030002) raise << "ELF type/machine 0x" << HEXWORD << e_machine_type << " isn't i386 executable\n" << die(); // unused: e_version. We only support version 1, and later versions will be backwards compatible. uint32_t e_entry = u32_in(&elf_contents[24]); uint32_t e_phoff = u32_in(&elf_contents[28]); // unused: e_shoff // unused: e_flags uint32_t e_ehsize = u16_in(&elf_contents[40]); if (e_ehsize < 52) raise << "Invalid binary; ELF header too small\n" << die(); uint32_t e_phentsize = u16_in(&elf_contents[42]); uint32_t e_phnum = u16_in(&elf_contents[44]); trace(90, "load") << e_phnum << " entries in the program header, each " << e_phentsize << " bytes long" << end(); // unused: e_shentsize // unused: e_shnum // unused: e_shstrndx set<uint32_t> overlap; // to detect overlapping segments for (size_t i = 0; i < e_phnum; ++i) load_segment_from_program_header(elf_contents, i, size, e_phoff + i*e_phentsize, e_ehsize, overlap); // initialize code and stack assert(overlap.find(STACK_SEGMENT) == overlap.end()); Mem.push_back(vma(STACK_SEGMENT)); assert(overlap.find(AFTER_STACK) == overlap.end()); // The stack grows downward. Reg[ESP].u = AFTER_STACK; Reg[EBP].u = 0; EIP = e_entry; // initialize args on stack // no envp for now // we wastefully use a separate page of memory for argv Mem.push_back(vma(ARGV_DATA_SEGMENT)); uint32_t argv_data = ARGV_DATA_SEGMENT; for (int i = argc-1; i >= /*skip 'subx_bin' and 'run'*/2; --i) { push(argv_data); for (size_t j = 0; j <= strlen(argv[i]); ++j) { assert(overlap.find(argv_data) == overlap.end()); // don't bother comparing ARGV and STACK write_mem_u8(argv_data, argv[i][j]); argv_data += sizeof(char); assert(argv_data < ARGV_DATA_SEGMENT + SEGMENT_ALIGNMENT); } } push(argc-/*skip 'subx_bin' and 'run'*/2); } void push(uint32_t val) { Reg[ESP].u -= 4; if (Reg[ESP].u < STACK_SEGMENT) { raise << "The stack overflowed its segment. " << "Maybe SPACE_FOR_SEGMENT should be larger? " << "Or you need to carve out an exception for the stack segment " << "to be larger.\n" << die(); } trace(Callstack_depth+1, "run") << "decrementing ESP to 0x" << HEXWORD << Reg[ESP].u << end(); trace(Callstack_depth+1, "run") << "pushing value 0x" << HEXWORD << val << end(); write_mem_u32(Reg[ESP].u, val); } void load_segment_from_program_header(uint8_t* elf_contents, int segment_index, size_t size, uint32_t offset, uint32_t e_ehsize, set<uint32_t>& overlap) { uint32_t p_type = u32_in(&elf_contents[offset]); trace(90, "load") << "program header at offset " << offset << ": type " << p_type << end(); if (p_type != 1) { trace(90, "load") << "ignoring segment at offset " << offset << " of non PT_LOAD type " << p_type << " (see http://refspecs.linuxbase.org/elf/elf.pdf)" << end(); return; } uint32_t p_offset = u32_in(&elf_contents[offset + 4]); uint32_t p_vaddr = u32_in(&elf_contents[offset + 8]); if (e_ehsize > p_vaddr) raise << "Invalid binary; program header overlaps ELF header\n" << die(); // unused: p_paddr uint32_t p_filesz = u32_in(&elf_contents[offset + 16]); uint32_t p_memsz = u32_in(&elf_contents[offset + 20]); if (p_filesz != p_memsz) raise << "Can't yet handle segments where p_filesz != p_memsz (see http://refspecs.linuxbase.org/elf/elf.pdf)\n" << die(); if (p_offset + p_filesz > size) raise << "Invalid binary; segment at offset " << offset << " is too large: wants to end at " << p_offset+p_filesz << " but the file ends at " << size << '\n' << die(); if (p_memsz >= SEGMENT_ALIGNMENT) { raise << "Code segment too small for SubX; for now please manually increase SEGMENT_ALIGNMENT.\n" << end(); return; } trace(90, "load") << "blitting file offsets (" << p_offset << ", " << (p_offset+p_filesz) << ") to addresses (" << p_vaddr << ", " << (p_vaddr+p_memsz) << ')' << end(); if (size > p_memsz) size = p_memsz; Mem.push_back(vma(p_vaddr)); for (size_t i = 0; i < p_filesz; ++i) { assert(overlap.find(p_vaddr+i) == overlap.end()); write_mem_u8(p_vaddr+i, elf_contents[p_offset+i]); overlap.insert(p_vaddr+i); } if (segment_index == 0 && End_of_program < p_vaddr+p_memsz) End_of_program = p_vaddr+p_memsz; } :(before "End Includes") // Very primitive/fixed/insecure ELF segments for now. // --- inaccessible: 0x00000000 -> 0x08047fff // code: 0x09000000 -> 0x09ffffff (specified in ELF binary) // data: 0x0a000000 -> 0x0affffff (specified in ELF binary) // --- heap gets mmap'd somewhere here --- // stack: 0xbdffffff -> 0xbd000000 (downward; not in ELF binary) // argv hack: 0xbf000000 -> 0xbfffffff (not in ELF binary) // --- reserved for kernel: 0xc0000000 -> ... const uint32_t START_HEAP = 0x0b000000; const uint32_t END_HEAP = 0xbd000000; const uint32_t STACK_SEGMENT = 0xbd000000; const uint32_t AFTER_STACK = 0xbe000000; const uint32_t ARGV_DATA_SEGMENT = 0xbf000000; // When updating the above memory map, don't forget to update `mmap`'s // implementation in the 'syscalls' layer. :(before "End Dump Info for Instruction") //? dump_stack(); // slow :(code) void dump_stack() { ostringstream out; trace(Callstack_depth+1, "run") << "stack:" << end(); for (uint32_t a = AFTER_STACK-4; a > Reg[ESP].u; a -= 4) trace(Callstack_depth+2, "run") << " 0x" << HEXWORD << a << " => 0x" << HEXWORD << read_mem_u32(a) << end(); trace(Callstack_depth+2, "run") << " 0x" << HEXWORD << Reg[ESP].u << " => 0x" << HEXWORD << read_mem_u32(Reg[ESP].u) << " <=== ESP" << end(); for (uint32_t a = Reg[ESP].u-4; a > Reg[ESP].u-40; a -= 4) trace(Callstack_depth+2, "run") << " 0x" << HEXWORD << a << " => 0x" << HEXWORD << read_mem_u32(a) << end(); } inline uint32_t u32_in(uint8_t* p) { return p[0] | p[1] << 8 | p[2] << 16 | p[3] << 24; } inline uint16_t u16_in(uint8_t* p) { return p[0] | p[1] << 8; } :(before "End Types") struct perr {}; :(code) ostream& operator<<(ostream& os, perr /*unused*/) { if (errno) os << ": " << strerror(errno); return os; } :(before "End Includes") #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdarg.h> #include <errno.h> #include <unistd.h>


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