Renesas TM V.3.20A Especificaciones descargar pdf (Pagina 315)

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Renesas Technology, Tools FAQs

Last Updated: September 5, 2001

Document Number: 01072303_e

In NC308WA V.3.00 Release 1, the "enter" instruction is output at the start of the function. But because it is not output in V.3.10

Release 2, the stack argument cannot be correctly referenced from the in-line assembly description. How can I generate the "enter"

instruction in this case?

The NC308WA optimization has been enhanced so that unnecessary "enter" instructions are not output. As the compiler does not

consider the processing contents of the in-line assembler statement, if an argument or automatic variable is not referenced at least

once somewhere other than within #pragma ASM to #pragma ENDASM, or asm(), the "enter" instruction is considered not

necessary and is not output.

NC308WA supports the following statement method for referencing C-language variables in in-line assembly: asm("...$$..." or

"...$@...", variable name);.

The compiler recognizes whether or not a variable is being used, and the "enter" instruction is generated as necessary. Other

methods used for referencing C-language variables will result in unreliable operations of the specified function or possible loss of

compatibility between compiler versions. Do not use other methods to reference variables or arguments or to set return values for

functions.

We recommend the following statement method:

[Example 1]

---------------------------------------------------

void memset(char *p, char c, unsigned short n)

{

asm(" PUSHM A1,R0,R3 "); // must exit from register to be used

asm(" MOV.L $$[FB],A1 ", d); // transfer argument d to A1

asm(" MOV.B $$[FB],R0L ", c); // transfer argument c to ROL

asm(" MOV.W $$[FB],R3 ", n); // transfer argument n to R3

asm(" SSTR.B ");

asm(" POPM A1,R0,R3 "); // original register

}

---------------------------------------------------

[Example 2]

---------------------------------------------------

void memset(char *p, char c, unsigned short n)

{

asm(" PUSHM A1,R0,R3 "); // must exit from register to be used

asm(" MOV.L $@,A1 ", d); // transfer argument d to A1

asm(" MOV.B $@,R0L ", c); // transfer argument c to ROL

asm(" MOV.W $@,R3 ", n); // transfer argument n to R3

asm(" SSTR.B ");

asm(" POPM A1,R0,R3 "); // return to original register

}

---------------------------------------------------

As an automatic variable, $$ substituted in the offset from the FB register value.

As an external variable, $$ replaces the symbol of the variable.

As a register variable, $$ replaces the register name.

$@, on the other hand, becomes the substitute for the operand that indicates an automatic, external or register variable. (The

compiler automatically determines the type of variable of $@.)

Due to optimization, function arguments and automatic variables may be modified into register variables. However, variables which

are used by asm("...$$..." or "...$@...", variable name); will not be modified in any way. For example, even a "$$" you intended to

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Renesas TM V.3.20A Especificaciones Pagina 315

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