Code Statement
in [ADA]
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From: Simon Wright on 19 May 2010 02:07 anon(a)att.net writes: > As for the example supplied I decide use the intel "nop" for simplicity > instead of using the codes for the attached processor. Ah! I see what you meant by "special project". > I prefer to use the Code Statement like the System.Machine_Code in SUN, > instead of using the inline-assembler of gnat\gcc. which forces the > following type of statements for non-native processors: > > ASM ( " .byte 0x90" ) ; -- intel x86 nop > ASM ( " .byte 0x02" ) ; -- attach processor instruction "Load R2" > ... > > And using the code statement allows the Ada compiler to emulate a small > limited assembler without all of the work\time in rewriting\expanding > the gcc "AS" to include the new processor. > > So, I see no problem in using code statement except for creating or > expand and recompiling the "system.machine_code" package. Unless Adacore > has crippled gnat's code statement routines. I'm not sure what http://www.adaic.com/standards/05rm/html/RM-13-8.html (2) means; does it give you a licence to use any type you lke? seems unlikely. > Now, the RM 13.8 (2), says that the code statement is qualified_expression > so what the problem. In Gnat, the ASM routines are handled by the > "Expand_Asm_Call" procedure ("exp_code" package) which expands the ASM > statement into a qualified_expression. Also, "P_Code_Statement" ("par-ch13" > package) directly processes code_statements as an qualified_expression. > Afterwards, the "Analyze_Code_Statement" ("sem-ch13" package) analyzes > should handle the code statements but this routine is where the error > message is generated. I expect the compiler is written to expect System.Machine_Code.Asm_Insn of the specific type defined in System.Machine_Code. You could write Asm_Insn'(Asm (".byte 0x90")); but it hardly seems worth the trouble. AdaCore have provided this as a "feature" I think -- see the GNAT RM, http://gcc.gnu.org/onlinedocs/gcc-4.5.0/gnat_rm/Machine-Code-Insertions.html
From: sjw on 19 May 2010 05:56 On May 19, 7:07 am, Simon Wright <si...(a)pushface.org> wrote: > I'm not sure what http://www.adaic.com/standards/05rm/html/RM-13-8.html > (2) means; does it give you a licence to use any type you lke? seems > unlikely. Sorry, I meant (4): "The qualified_expression is expected to be of any type." Compare with (5): "The qualified_expression shall be of a type declared in package System.Machine_Code."
From: AdaMagica on 19 May 2010 06:20
On 19 Mai, 11:56, sjw <simon.j.wri...(a)mac.com> wrote: > On May 19, 7:07 am, Simon Wright <si...(a)pushface.org> wrote: > > > I'm not sure whathttp://www.adaic.com/standards/05rm/html/RM-13-8.html > > (2) means; does it give you a licence to use any type you lke? seems > > unlikely. > > Sorry, I meant (4): "The qualified_expression is expected to be of any > type." This is a Name Resolution Rule used for overload resolution. As far as overloading is concernded, any type can do. > Compare with (5): "The qualified_expression shall be of a type > declared in package System.Machine_Code." This is a Legality Rule and applied only after overload resolution. So this is where code becomes illegal when other types are used. |