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rendering.c: fast cos from sin calculation, with lossy fast_sqrt()

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veclav talica
2024-07-28 14:39:23 +03:00
parent c59708d619
commit ea4d12212c
3 changed files with 154 additions and 129 deletions
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82
src/system/linux/elf.c
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@ -12,57 +12,57 @@
#include <string.h>
bool infer_elf_section_bounds(const char *const restrict name,
const char **restrict vm_start,
const char **restrict vm_end)
const char **restrict vm_start,
const char **restrict vm_end)
{
bool result = false;
char buf[PATH_MAX];
ssize_t l = readlink("/proc/self/exe", buf, PATH_MAX);
if (l == -1)
goto ERR_CANT_READLINK;
buf[l] = 0; /* readlink() doesn't write a terminator */
bool result = false;
char buf[PATH_MAX];
ssize_t l = readlink("/proc/self/exe", buf, PATH_MAX);
if (l == -1)
goto ERR_CANT_READLINK;
buf[l] = 0; /* readlink() doesn't write a terminator */
int elf = open(buf, O_RDONLY);
if (elf == -1)
goto ERR_CANT_OPEN_SELF;
int elf = open(buf, O_RDONLY);
if (elf == -1)
goto ERR_CANT_OPEN_SELF;
/* elf header */
Elf64_Ehdr ehdr;
read(elf, &ehdr, sizeof ehdr);
if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
ehdr.e_ident[EI_MAG3] != ELFMAG3)
goto ERR_NOT_ELF;
/* elf header */
Elf64_Ehdr ehdr;
read(elf, &ehdr, sizeof ehdr);
if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
ehdr.e_ident[EI_MAG3] != ELFMAG3)
goto ERR_NOT_ELF;
/* section header string table */
Elf64_Shdr shstrdr;
lseek(elf, ehdr.e_shoff + ehdr.e_shstrndx * sizeof (Elf64_Shdr), SEEK_SET);
read(elf, &shstrdr, sizeof shstrdr);
char *sh = malloc(shstrdr.sh_size);
lseek(elf, shstrdr.sh_offset, SEEK_SET);
read(elf, sh, shstrdr.sh_size);
/* section header string table */
Elf64_Shdr shstrdr;
lseek(elf, ehdr.e_shoff + ehdr.e_shstrndx * sizeof (Elf64_Shdr), SEEK_SET);
read(elf, &shstrdr, sizeof shstrdr);
char *sh = malloc(shstrdr.sh_size);
lseek(elf, shstrdr.sh_offset, SEEK_SET);
read(elf, sh, shstrdr.sh_size);
/* walk sections searching for needed name */
lseek(elf, ehdr.e_shoff, SEEK_SET);
for (size_t s = 0; s < ehdr.e_shnum; ++s) {
Elf64_Shdr shdr;
read(elf, &shdr, sizeof shdr);
/* walk sections searching for needed name */
lseek(elf, ehdr.e_shoff, SEEK_SET);
for (size_t s = 0; s < ehdr.e_shnum; ++s) {
Elf64_Shdr shdr;
read(elf, &shdr, sizeof shdr);
if (strcmp(&sh[shdr.sh_name], name) == 0) {
result = true;
*vm_start = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr;
*vm_end = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr + shdr.sh_size;
break;
}
}
if (strcmp(&sh[shdr.sh_name], name) == 0) {
result = true;
*vm_start = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr;
*vm_end = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr + shdr.sh_size;
break;
}
}
free(sh);
free(sh);
ERR_NOT_ELF:
close(elf);
close(elf);
ERR_CANT_OPEN_SELF:
ERR_CANT_READLINK:
return result;
return result;
}