liblinux++

A hosted C++ runtime without any libc.
git clone git://henryandlizzy.uk/liblinux++
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x86_64.S (806B)

      1 # Syscall numbers https://www.chromium.org/chromium-os/developer-library/reference/linux-constants/syscalls/#x86_64-64-bit
      2 
      3 #include "NR_x86_64.h"
      4 
      5 .intel_syntax noprefix
      6 
      7 .global start
      8 
      9 .text
     10 
     11 start:	# start is the entry point known to the linker
     12 	mov	edi,	[rsp]		# get argc from the stack
     13 	lea	rsi,	[rsp+8]		# take the address of argv from the stack
     14 	lea	rdx,	[rsp+16]	# take the address of envp from the stack
     15 	call	main			# %edi, %rsi, %rdx are the three args (of which first two are C standard) to main
     16 	mov	rdi,	rax
     17 	jmp exit
     18 
     19 .macro extern_alias, name
     20 .global \name
     21 \name:
     22 .endm
     23 
     24 .macro extern, name
     25 .section .text.\name
     26 extern_alias \name
     27 .endm
     28 
     29 .macro _syscall, num, impl
     30 	mov	rax,	\num
     31 	push	r11
     32 	mov	r10,	rcx
     33 	syscall
     34 	pop	r11
     35 	ret
     36 .endm
     37 
     38 #define SYS(x) _syscall __NR_##x
     39 
     40 #include "syscalls.h"