On 16 February 2014 23:37, Torsten Bergmann <[email protected]> wrote:
> Hi,
>
> I'm trying to mimic the following C/C++ example in NativeBoots to allow
> random number
> generation on windows:
>
> https://gist.github.com/kbjorklu/6317361
>
> When I combine the flags in Pharo using "|" in the same way like in the
> first function call
> of the example:
>
> acquireContextExample1
> NBFFICallout stdcall: #(BOOL CryptAcquireContextA(HCRYPTPROV self, 0, 0,
> PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) module: #advapi32
>
> I get an error 'comma expected'. Looks like the NBFnSpecParser does not
> allow
> expression evaluation like CRYPT_VERIFYCONTEXT | CRYPT_SILENT. Will this
> be possible
> in future versions?
>
> Nonetheless I tried to continue and since I defined:
> CRYPT_VERIFYCONTEXT := 16rF0000000.
> CRYPT_SILENT := 16r00000040.
>
> I evaluated manually and tried to use the harcoded value directly:
>
> acquireContextExample2
>
> "Retrieves information about the current console font."
> <primitive: 'primitiveNativeCall' module: 'NativeBoostPlugin'>
>
> ^ NBFFICallout stdcall: #(BOOL CryptAcquireContextA(HCRYPTPROV
> self, 0, 0, PROV_RSA_FULL, 16rF0000040)) module: #advapi32
>
>
> but this returns another error when converting using #asDWord:
>
> (16rF0000040 i4) exceeds doubleword (32bit) range
>
> in an AJImmediate but 16rF0000040. Looks like it is treated as unsiged
> since
>
> 16rF0000040 asUImm32 asDWord
>
> works. How to specifiy the number directly but as unsigned?
>
> To reproduce:
> - take a fresh Pharo3.0 Latest update: #30759
> - load "OSWindows" from config browser to get the core and other packages
> - load "OS-Windows-Cryptography" package/mcz from
> smalltalkhub.com/#!/~OS/OS-Windows
> - evaluate WinCryptoProvider new acquireContextExample2 or
> WinCryptoProvider new acquireContextExample1
>
> Any helping hand in converting the example would be appreciated.
>
> Thx
> T.
>
Yes, i am aware of this problem.
(16rF0000040 i4) exceeds doubleword (32bit) range
i4 means signed integer 4 bytes..
the mantissa 16rF0000040 , simply don't fits, because it is > 2^31-1, which
is max for 32-bit integer.
The class responsible for passing constants is NBFFIConst:
Integer>>asNBExternalType: gen
"integer value in callout argument description array are pushed
directly on stack
#( 100 ) - an integer value argument = 100
"
^ NBFFIConst value: (self )
the code generator, uses:
emitPush: gen
gen asm push: ((gen asm imm: value) size: 4)
and #imm: sends #asImm to the value, which by default turns integer into a
signed immediate:
Integer>>asImm
"Convert integer value into a signed immediate operand"
^ AJImmediate new ivalue: self
unfortunately, there is no easy way to work around this: if you change it
to unsigned (uvalue:),
then you have another problem, but now with all negative integer constants
(like -1).
But you can work that around: use a 32-bit complement
of unsigned 16rF0000040
to signed one, which ends up with identical 32-bit value:
16rF0000040 - 16r100000000 => -268435392
test:
(16r100000000 - 268435392) hex '16rF0000040'
--
Best regards,
Igor Stasenko.
