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    Length: 3072 (0xc00)
    Types: TextFile
    Names: »NATLOG.SRC«

└─⟦c9df7130d⟧ Bits:30005915 Pascal MT+ Release 5.2 (Jet-80)
    └─ ⟦this⟧ »NATLOG.SRC« 

TextFile

;   intrinsic function for calculating natural log
;
	NAME NATLOG  
	ENTRY LN,L134
	EXT FPSQR,RNGERR
	INCLUDE DEFLT.SRC
	INCLUDE FCTMAC.SRC
;
L118	EQU	FPSQR
;
;
; function ln( x: real ): real;
; const	c1 = 2.8853913;
; 	c3 = 0.9614706;
; 	c5 = 0.59897865;
; 	sqrtp5 = 0.7071068;
; 	loge2 = 0.6931472;
; var y: record
; 	case char of
; 	  'a': ( a: real );
; 	  'b': ( b1, b2, b3, b4: 0..255 )
; 	end;
;     z, z2: real;
;     i: integer;
; begin
L134:
ln:
	ENTR	D,2,14

	PUSH 	IX		;check if x is a negative number
	POP	H
	LXI	B,10		;byte containing sign bit of mantissa
	DAD	B
	BIT	7,M		;test bit
	JNZ	RNGERR		;negative number, error message and abort

;     if x = 1.0 then ln := 0.0
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,8
	DADD	B
	LXI	B,4
	LDIR
	LXI	H,320
	MOV	D,A
	MOV	E,A
	PUSH	H
	PUSH	D
	EQUL	D,-4
	JNC	FC2193
;     else begin
	MOV	H,A
	MOV	L,A
	MOV	D,A
	MOV	E,A
	PUSH	H
	PUSH	D
	LXI	H,3
	DADD	S
	XCHG
	PUSH	IX
	POP	H
	LXI	B,15
	DADD	B
	XCHG
	LXI	B,4
	LDDR
	POP	H
	POP	H
	JMP	FC2206
FC2193
; 	y.a := x;
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,8
	DADD	B
	LXI	B,4
	LDIR
	LXI	H,3
	DADD	S
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-10
	DADD	B
	XCHG
	LXI	B,4
	LDDR
	POP	H
	POP	H
; 	i := (y.b1 + 128) mod 256 - 128;
	MOV	H,A
	MOV	L,-10(IX)
	LXI	D,128
	DADD	D,0
	LXI	D,256
	MMOD	D,0
	LXI	D,-128
	DADD	D,0
	MOV	-8(IX),H
	MOV	-9(IX),L
; 	y.b1 := 0;
	MOV	-10(IX),A
; 	z := (y.a - sqrtp5) / (y.a + sqrtp5);
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-13
	DADD	B
	LXI	B,4
	LDIR
	LXI	H,90
	LXI	D,-32135
	PUSH	H
	PUSH	D
	DSUB	D,-4
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-13
	DADD	B
	LXI	B,4
	LDIR
	LXI	H,90
	LXI	D,-32135
	PUSH	H
	PUSH	D
	DADD	D,-4
	FDVD	D,-4
	LXI	H,3
	DADD	S
	XCHG
	PUSH	IX
	POP	H
	XCHG
	LXI	B,4
	LDDR
	POP	H
	POP	H
; 	z2 := sqr( z );
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	DCX	H
	DCX	H
	DCX	H
	LXI	B,4
	LDIR
	CALL	L118
	LXI	H,3
	DADD	S
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-4
	DADD	B
	XCHG
	LXI	B,4
	LDDR
	POP	H
	POP	H
; 	ln := (((c5*z2 + c3)*z2 + c1)*z - 0.5 + i) * loge2;
	LXI	H,76
	LXI	D,-21675
	PUSH	H
	PUSH	D
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-7
	DADD	B
	LXI	B,4
	LDIR
	MULT	D,-4
	LXI	H,123
	LXI	D,4471
	PUSH	H
	PUSH	D
	DADD	D,-4
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	LXI	B,-7
	DADD	B
	LXI	B,4
	LDIR
	MULT	D,-4
	LXI	H,604
	LXI	D,21792
	PUSH	H
	PUSH	D
	DADD	D,-4
	LXI	H,-4
	DADD	S
	SPHL
	XCHG
	PUSH	IX
	POP	H
	DCX	H
	DCX	H
	DCX	H
	LXI	B,4
	LDIR
	MULT	D,-4
	LXI	H,64
	MOV	D,A
	MOV	E,A
	PUSH	H
	PUSH	D
	DSUB	D,-4
	MOV	L,-9(IX)
	MOV	H,-8(IX)
	PUSH	H
	CVTF	B
	DADD	D,-4
	LXI	H,88
	LXI	D,-18164
	PUSH	H
	PUSH	D
	MULT	D,-4
	LXI	H,3
	DADD	S
	XCHG
	PUSH	IX
	POP	H
	LXI	B,15
	DADD	B
	XCHG
	LXI	B,4
	LDDR
	POP	H
	POP	H
;     end
; end;
FC2206
	EXIT	D,4
;
«eof»