Print Page - Declare constant in function body

Title: Declare constant in function body
Post by: CLR on November 20, 2016, 09:57:51 PM

I wrote the following function with POASM.

.data
value REAL8 2.026119

.code

my_cos proc
	push ebp
	mov ebp, esp

	fld qword ptr [value]
	fcos

	pop ebp
	ret
my_cos endp

I wonder if I can declare "value" inside function body.

I tried fld 2.026119 and I got the error "Invalid combination of opcode and operands (or wrong CPU setting)."

Title: Re: Declare constant in function body
Post by: jj2007 on November 20, 2016, 11:09:54 PM

There is no direct opcode fld 2.026119, but if you prefer this simple syntax to a REAL8 in the .data section, it should be easy to set up a PoAsm macro. Here are some Masm equivalents for your inspiration.

include \masm32\MasmBasic\MasmBasic.inc ; download (http://masm32.com/board/index.php?topic=94.0)
Init
fldpi ; these are real opcodes
fldl2e
fldl2t
fldlg2
fld FP8(2.0261191) ; this is a Masm32 macro
FpuPush (http://www.webalice.it/jj2006/MasmBasicQuickReference.htm#Mb1189) 2.0261192 ; this is a MasmBasic macro
deb (http://www.webalice.it/jj2006/MasmBasicQuickReference.htm#Mb1019) 4, "Fpu", ST(0), ST(1), ST(2), ST(3), ST(4), ST(5), ST(6) ; use debug macro to display ST(0)
EndOfCode

Output:

Code Select

Fpu
ST(0)           2.026119232177734375
ST(1)           2.026119099999999840
ST(2)           0.3010299956639811952
ST(3)           3.321928094887362348
ST(4)           1.442695040888963407
ST(5)           3.141592653589793238
ST(6)           0.0

Title: Re: Declare constant in function body
Post by: TimoVJL on November 20, 2016, 11:38:02 PM

something to test

Code Select

MVR8 MACRO value
	LOCAL varr8
	.data
	varr8 REAL8 value
	.code
	EXITM <addr varr8>
ENDM

.code

my_cos proc
.data
value REAL8 2.026119
.code
	push ebp
	mov ebp, esp

	fld qword ptr [value]
	fld qword ptr MVR8(2.026119)
	fcos

	pop ebp
	ret
my_cos endp

Title: Re: Declare constant in function body
Post by: CLR on November 22, 2016, 12:46:20 AM

Thank you for the help, jj2007 & TimoVJL.

Pelles C forum

Assembly language => Assembly discussions => Topic started by: CLR on November 20, 2016, 09:57:51 PM