initial checkin from subversion

floatArithmetics/fltarith.asm

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+; fltarith.asm   show some simple C code and corresponding nasm code
+;                the nasm code is one sample, not unique
+;
+; compile  nasm -f elf -l fltarith.lst  fltarith.asm
+; link     gcc -o fltarith  fltarith.o
+; run      fltarith
+;
+; the output from running fltarith and fltarithc is:	
+; c=5.0, a=3.000000e+00, b=4.000000e+00, c=5.000000e+00
+; c=a+b, a=3.000000e+00, b=4.000000e+00, c=7.000000e+00
+; c=a-b, a=3.000000e+00, b=4.000000e+00, c=-1.000000e+00
+; c=a*b, a=3.000000e+00, b=4.000000e+00, c=1.200000e+01
+; c=c/a, a=3.000000e+00, b=4.000000e+00, c=4.000000e+00
+;
+;The file  fltarith.c  is:
+;  #include <stdio.h>
+;  int main()
+;  { 
+;    double a=3.0, b=4.0, c;
+;
+;    c=5.0;
+;    printf("%s, a=%e, b=%e, c=%e\n","c=5.0", a, b, c);
+;    c=a+b;
+;    printf("%s, a=%e, b=%e, c=%e\n","c=a+b", a, b, c);
+;    c=a-b;
+;    printf("%s, a=%e, b=%e, c=%e\n","c=a-b", a, b, c);
+;    c=a*b;
+;    printf("%s, a=%e, b=%e, c=%e\n","c=a*b", a, b, c);
+;    c=c/a;
+;    printf("%s, a=%e, b=%e, c=%e\n","c=c/a", a, b, c);
+;    return 0;
+; }
+
+        extern printf		; the C function to be called
+
+%macro	pabc 1			; a "simple" print macro
+	section	.data
+.str	db	%1,0		; %1 is macro call first actual parameter
+	section .text
+				; push onto stack backwards 
+	push	dword [c+4]	; double c (bottom)
+	push	dword [c]	; double c
+	push	dword [b+4]	; double b (bottom)
+	push	dword [b]	; double b 
+	push	dword [a+4]	; double a (bottom)
+	push	dword [a]	; double a
+	push	dword .str 	; users string
+        push    dword fmt       ; address of format string
+        call    printf          ; Call C function
+        add     esp,32          ; pop stack 8*4 bytes
+%endmacro
+	
+	section	.data  		; preset constants, writeable
+a:	dq	3.333333333	; 64-bit variable a initialized to 3.0
+b:	dq	4.444444444	; 64-bit variable b initializes to 4.0
+five:	dq	5.0		; constant 5.0
+fmt:    db "%s, a=%e, b=%e, c=%e",10,0	; format string for printf
+	
+	section .bss 		; unitialized space
+c:	resq	1		; reserve a 64-bit word
+
+	section .text		; instructions, code segment
+	global	main		; for gcc standard linking
+main:				; label
+	
+lit5:				; c=5.0;
+	fld	qword [five]	; 5.0 constant
+	fstp	qword [c]	; store into c
+	pabc	"c=5.0"		; invoke the print macro
+	
+addb:				; c=a+b;
+	fld	qword [a] 	; load a (pushed on flt pt stack, st0)
+	fadd	qword [b]	; floating add b (to st0)
+	fstp	qword [c]	; store into c (pop flt pt stack)
+	pabc	"c=a+b"		; invoke the print macro
+	
+subb:				; c=a-b;
+	fld	qword [a] 	; load a (pushed on flt pt stack, st0)
+	fsub	qword [b]	; floating subtract b (to st0)
+	fstp	qword [c]	; store into c (pop flt pt stack)
+	pabc	"c=a-b"		; invoke the print macro
+	
+mulb:				; c=a*b;
+	fld	qword [a]	; load a (pushed on flt pt stack, st0)
+	fmul	qword [b]	; floating multiply by b (to st0)
+	fstp	qword [c]	; store product into c (pop flt pt stack)
+	pabc	"c=a*b"		; invoke the print macro
+	
+diva:				; c=c/a;
+	fld	qword [c] 	; load c (pushed on flt pt stack, st0)
+	fdiv	qword [a]	; floating divide by a (to st0)
+	fstp	qword [c]	; store quotient into c (pop flt pt stack)
+	pabc	"c=c/a"		; invoke the print macro
+
+        mov     eax,0           ; exit code, 0=normal
+	ret			; main returns to operating system
+
+