BITS 64
GLOBAL lrotate:function ; [1]
- GLOBAL greet:function ; [1]
+ GLOBAL greet_s:function ; [1]
+ GLOBAL greet_m:function ; [1]
GLOBAL asmstr:data asmstr.end-asmstr ; [2]
GLOBAL textptr:data 8 ; [2]
GLOBAL selfptr:data 8 ; [2]
pop rbp
ret
-; prototype: void greet(void);
-;; rdi - rsi - rdx - rcx - r8 - r9
-;; rbx, rbp, r12-r15 are saved
-greet:
+;; prototype: void greet_*(void);
+;;
+;; Arguments are: rdi - rsi - rdx - rcx - r8 - r9
+;; Registers: rbx, rbp, r12-r15 are saved
+;; greet_s() is Small PIC model, greet_m() is Medium PIC model
+;; (Large model cannot be linked with other code)
+;;
+greet_s:
mov rax,[rel commvar wrt ..got] ; &commvar
mov rcx,[rax] ; commvar
mov rax,[rel integer wrt ..got] ; &integer
xor eax,eax ; No fp arguments
jmp printf wrt ..plt ; [10]
+greet_m:
+ push r15 ; Used by convention...
+ lea r15,[rel _GLOBAL_OFFSET_TABLE_]
+ mov rax,[rel commvar wrt ..got] ; &commvar
+ mov rcx,[rax] ; commvar
+ mov rax,[rel integer wrt ..got] ; &integer
+ mov rsi,[rax]
+ lea rdx,[rsi+1]
+ mov rax,localint wrt ..gotoff ; &localint - r15
+ mov [rax+r15],rdx ; localint = integer+1
+ mov rax,localptr wrt ..gotoff ; &localptr - r15
+ mov rax,[rax+r15] ; localptr
+ mov rdx,[rax] ; *localptr = localint
+ mov rdi,printfstr wrt ..gotoff ; &printfstr - r15
+ add rdi,r15 ; &printfstr
+ xor eax,eax ; No fp arguments
+ pop r15
+ jmp printf wrt ..plt ; [10]
+
SECTION .data
; a string
; some pointers
localptr dq localint ; [5] [17]
-textptr dq greet wrt ..sym ; [15]
+textptr dq greet_s wrt ..sym ; [15]
selfptr dq selfptr wrt ..sym ; [16]
SECTION .bss
#include <inttypes.h>
extern long lrotate(long, int);
-extern void greet(void);
+extern void greet_s(void);
+extern void greet_m(void);
extern int8_t asmstr[];
extern void *selfptr;
extern void *textptr;
printf("The integers here should be 1234, 1235 and 4321:\n");
integer = 1234;
commvar = 4321;
+ greet_s();
+ greet_m();
- greet();
-
- printf("These pointers should be equal: %p and %p\n", &greet, textptr);
+ printf("These pointers should be equal: %p and %p\n", &greet_s, textptr);
printf("So should these: %p and %p\n", selfptr, &selfptr);