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| author | Přemysl Janouch <p.janouch@gmail.com> | 2016-12-25 01:37:06 +0100 |
|---|---|---|
| committer | Přemysl Janouch <p.janouch@gmail.com> | 2016-12-25 01:56:42 +0100 |
| commit | d52dcd1de717d6a38c004814c340c9e1187aa481 (patch) | |
| tree | 88e4931eeed017e226d87863ca4a440fc1b28a78 | |
| parent | 29062e6c441f1bf34a9105b775cbde8955646388 (diff) | |
| download | bfc-d52dcd1de717d6a38c004814c340c9e1187aa481.tar.gz bfc-d52dcd1de717d6a38c004814c340c9e1187aa481.tar.xz bfc-d52dcd1de717d6a38c004814c340c9e1187aa481.zip | |
Shorter epilog once again
Even though it's more cryptic now.
| -rw-r--r-- | bfc-amd64.c | 39 |
1 files changed, 18 insertions, 21 deletions
diff --git a/bfc-amd64.c b/bfc-amd64.c index 9cb5b98..cf34b84 100644 --- a/bfc-amd64.c +++ b/bfc-amd64.c @@ -588,7 +588,7 @@ main (int argc, char *argv[]) #error Target not supported #endif - CODE ("\xB8") DD (SYS_EXIT) // mov eax, 0x3c + CODE ("\xB8") DD (SYS_EXIT) // mov eax, "SYS_EXIT" CODE ("\x48\x31\xFF") // xor rdi, rdi CODE ("\x0F\x05") // syscall @@ -608,22 +608,27 @@ main (int argc, char *argv[]) CODE ("\xBF") DD (1) // mov edi, "EXIT_FAILURE" CODE ("\x0F\x05") // syscall - size_t read_offset = buffer.len; - CODE ("\x50") // push rax -- save tape position - CODE ("\xB8") DD (SYS_READ) // mov eax, "SYS_READ" - CODE ("\xBF") DD (0) // mov edi, "STDIN_FILENO" - CODE ("\x66\x6A\x00") // push word 0 -- the default value for EOF + size_t io_offset = buffer.len; CODE ("\x48\x89\xE6") // mov rsi, rsp -- the char starts at rsp CODE ("\xBA") DD (1) // mov edx, 1 -- count CODE ("\x0F\x05") // syscall - CODE ("\x66\x5B") // pop bx CODE ("\x48\x83\xF8\x00") // cmp rax, 0 - CODE ("\x48\x8D\x35") DD (8) // lea rsi, [rel read_message] - CODE ("\x0F\x8C") // jl "fatal_offset" -- write failure message - DD ((intptr_t) fatal_offset - (intptr_t) (buffer.len + 4)) + CODE ("\x4C\x89\xE6") // mov rsi, r12 + CODE ("\x7C") // jl "fatal_offset" -- write failure message + DB ((intptr_t) fatal_offset - (intptr_t) (buffer.len + 1)) + CODE ("\x66\x5B") // pop bx CODE ("\x58") // pop rax -- restore tape position CODE ("\xC3") // ret + + size_t read_offset = buffer.len; + CODE ("\x50") // push rax -- save tape position + CODE ("\xB8") DD (SYS_READ) // mov eax, "SYS_READ" + CODE ("\xBF") DD (0) // mov edi, "STDIN_FILENO" + CODE ("\x66\x6A\x00") // push word 0 -- the default value for EOF + CODE ("\x4C\x8D\x25") DD (2) // lea r12, [rel read_message] + CODE ("\xEB") // jmp "io_offset" + DB ((intptr_t) io_offset - (intptr_t) (buffer.len + 1)) CODE ("fatal: read failed\n\0") size_t write_offset = buffer.len; @@ -631,17 +636,9 @@ main (int argc, char *argv[]) CODE ("\xB8") DD (SYS_WRITE) // mov eax, "SYS_WRITE" CODE ("\xBF") DD (1) // mov edi, "STDOUT_FILENO" CODE ("\x66\x53") // push bx - CODE ("\x48\x89\xE6") // mov rsi, rsp -- the char starts at rsp - CODE ("\xBA") DD (1) // mov edx, 1 -- count - CODE ("\x0F\x05") // syscall - CODE ("\x66\x5B") // pop bx - - CODE ("\x48\x83\xF8\x00") // cmp rax, 0 - CODE ("\x48\x8D\x35") DD (8) // lea rsi, [rel write_message] - CODE ("\x0F\x8C") // jl "fatal_offset" -- write failure message - DD ((intptr_t) fatal_offset - (intptr_t) (buffer.len + 4)) - CODE ("\x58") // pop rax -- restore tape position - CODE ("\xC3") // ret + CODE ("\x4C\x8D\x25") DD (2) // lea r12, [rel write_message] + CODE ("\xEB") // jmp "io_offset" + DB ((intptr_t) io_offset - (intptr_t) (buffer.len + 1)) CODE ("fatal: write failed\n\0") // Now that we know where each instruction is, fill in relative jumps |