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[BUG/PRB.] ADJUST THE PRECISION OF THE FLOATING-POINT CONSTANTS
February 2024
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CCB
1. BUG:
There is a test program:
*PROC testfloatingpointconst
SET DECIMALS TO 2
?INT(4294967295/16777216) && Displays 256 if SET("DECIMALS")<=3
SET DECIMALS TO 10
?INT(4294967295/16777216) && Displays 255 if SET("DECIMALS")>=4
RETURN
* END OF PROC TESTFLOATINGPOINTCONST.
We think they will display 255, but:
?INT(4294967295/16777216) && Displays 256 if SET("DECIMALS")<=3
2. CAUSE:
There are some BUGs in the following code.
3. RESOLUTION:
We can write some code to fix the BUG.
Label51701a ::
mov ecx , dword ptr [ Data9370f0 ] ;0x0051701a : 8b0df0709300
mov eax , dword ptr [ Data9393ac ] ;0x00517020 : a1ac939300
add ecx , 02Ch ;0x00517025 : 83c12c
mov dword ptr [ Data9370f0 ] , ecx ;0x00517028 : 890df0709300
mov byte ptr [ecx] , 04Eh ;0x0051702e : c6014e
movzx edx ,byte ptr [eax] ;0x00517031 : 0fb610
inc eax ;0x00517034 : 40
mov dword ptr [ ecx + 4 ] , edx ;0x00517035 : 895104
movzx edx ,byte ptr [eax] ;0x00517038 : 0fb610
inc eax ;0x0051703b : 40
mov dword ptr [ ecx + 8 ] , edx ;0x0051703c : 895108
add eax , 08h ;0x0051703f : 83c008
fld qword ptr [ eax - 8 ] ;0x00517042 : dd40f8
mov dword ptr [ Data9393ac ] , eax ;0x00517045 : a3ac939300
fstp qword ptr [ ecx + 16 ] ;0x0051704a : dd5910
;
; ----------------------------------------------------------------------------
; VFP 9.0 FIX - ADJUST THE PRECISION OF THE FLOATING-POINT CONSTANTS
; February 2024
; ----------------------------------------------------------------------------
; CCB
;
; In vfp9 (and vfp6, vfp7, vfp8), sometimes the value of a floating-point constant is relative to SET("DECIMALS"), for example,
; 4294967295/16777216 = 255.99999994039535520 (0x406FFFFFFFE00000)
; SET DECIMALS TO 2
; 4294967295/16777216 = 255.99???????????????
; SET DECIMALS TO 6
; 4294967295/16777216 = 255.999999???????????
; SET DECIMALS TO 10
; 4294967295/16777216 = 255.9999999403???????
; SET DECIMALS TO 15
; 4294967295/16777216 = 255.999999940395355??
; In Visual FoxPro Advanced, it will set 15 or more valid digits for the floating-point constants, for example,
; 4294967295/16777216 = 255.99999994039535520 (0x406FFFFFFFE00000)
; SET DECIMALS TO 2
; 4294967295/16777216 = 255.999999940395?????
; SET DECIMALS TO 6
; 4294967295/16777216 = 255.999999940395?????
; SET DECIMALS TO 10
; 4294967295/16777216 = 255.999999940395?????
; SET DECIMALS TO 15
; 4294967295/16777216 = 255.999999940395355??
;
; 2024/2/3, by ccb
;
cmp dword ptr vfpa_sys9146_data,00h
je Label51704d
cmp byte ptr [eax],0CCh
jne Label51704d
cmp dword ptr [ ecx + 8 ],0Fh
jge Label51704d
sub esp , 08h
fld qword ptr [ ecx + 16 ]
fld st(0)
fabs
fldlg2
fxch st(1)
fyl2x
fld st(0)
fistp dword ptr [ esp ]
mov eax,dword ptr [ esp ]
cmp eax,80000000h
je Label51704b
and eax,80000000h
test eax,eax
jne Label51704b
mov eax,0
IFDEF RAX
push esi
lea esi , dword ptr [ Data922438 ]
fadd qword ptr [ 8 * eax + esi ]
pop esi
ELSE
fadd qword ptr [ 8 * eax + offset Data922438 ]
ENDIF
mov eax,0Ah
IFDEF RAX
push esi
lea esi , dword ptr [ Data922438 ]
fadd qword ptr [ 8 * eax + esi ]
pop esi
ELSE
fadd qword ptr [ 8 * eax + offset Data922438 ]
ENDIF
fistp dword ptr [ esp ]
mov eax,0Fh
sub eax,dword ptr [ esp ]
cmp eax,0
jl Label51704c
cmp eax,0Fh
jg Label51704c
cmp eax,dword ptr [ ecx + 8 ]
jle Label51704c
cmp dword ptr [ ecx + 8 ],00h
jne Label51704a
inc dword ptr [ ecx + 4 ]
Label51704a ::
sub eax,dword ptr [ ecx + 8 ]
add dword ptr [ ecx + 8 ],eax
add dword ptr [ ecx + 4 ],eax
cmp dword ptr [ ecx + 4 ],028h
jbe Label51704c
mov dword ptr [ ecx + 4 ],028h
jmp Label51704c
Label51704b ::
fstp st(0)
mov eax,0Fh
cmp eax,dword ptr [ ecx + 8 ]
jle Label51704c
mov dword ptr [ ecx + 8 ],0Fh
mov dword ptr [ ecx + 4 ],11h
jmp Label51704c
Label51704c ::
fstp st(0)
add esp , 08h
jmp Label51704d
Label51704d ::
ret ;0x0051704d : c3
4. APPLIES TO:
VFP 6.0.8167.0
VFP 6.0.8961.0 (SP5)
VFP 7.0.0.9262
VFP 7.0.0.9465 (SP1)
VFP 8.0.0.2521
VFP 8.0.0.3117 (SP1)
VFP 9.0.0.2412
VFP 9.0.0.3504 (SP1)
VFP 9.0.0.4611 (SP2)
VFP 9.0.0.5015 (SP2)
VFP 9.0.0.5411 (SP2)
VFP 9.0.0.5721 (SP2)
VFP 9.0.0.5815 (SP2)
VFP 9.0.0.6303 (SP2)
VFP 9.0.0.6602 (SP2)
VFP 9.0.0.7423 (SP2)
The bug has been fixed in VFP Advanced.
5. REFERENCE WEBSITES:
1, baiyujia.com:
http://www.baiyujia.com
http://www.baiyujia.com/vfpdocuments/f_vfp9fix303.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix23.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix24.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix97.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix98.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix123.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix124.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix255.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix256.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix257.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix258.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix259.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix260.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix305.asp
http://www.baiyujia.com/vfpdocuments/f_vfp9fix306.asp
6. OTHER:
For reference only, there is no guarantees.
Any questions or suggestions, please send me an email at ccb2000@163.com.
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