strchr definition

strchr definition

[brz-systemd-dev]

I seem to be finding conflicting definitions of strchr

strcat(2)
	char* strchr(char *s, char c)

/sys/src/libc/port/strchr.c
	char* strchr(char *s, int c)

/sys/include/libc.h:/strchr/
	extern	char*	strchr(char*, int);

So it seems like it takes an int, rather than a char.
But referencing the 386 asm, this is seen.
/sys/src/libc/386/strchr.s:4: MOVB c+4(FP), AX
                                           (^ Why a 16-bit register?)
Is there a reason for these seemingly divergent definitions?

Re: [9front] strchr definition

[Iruatã Souza]

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Em 07/12/2014 03:06, <brz-systemd-dev@intma.in> escreveu:
>
> I seem to be finding conflicting definitions of strchr
>
> strcat(2)
>         char* strchr(char *s, char c)
>
> /sys/src/libc/port/strchr.c
>         char* strchr(char *s, int c)
>
> /sys/include/libc.h:/strchr/
>         extern  char*   strchr(char*, int);
>
> So it seems like it takes an int, rather than a char.
> But referencing the 386 asm, this is seen.
> /sys/src/libc/386/strchr.s:4: MOVB c+4(FP), AX
>                                            (^ Why a 16-bit register?)
> Is there a reason for these seemingly divergent definitions?

The 386 assembler does not do 16 bit, i.e. AX there is 32 bits long.

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Re: [9front] strchr definition

[cinap_lenrek]

in plan9 assembler, AX is like EAX (or RAX in 64bit mode) in intel assembler.
the operand size is specified by the instruction like MOVB, MOVW, MOVL and MOVQ.

in the MOVB c+4(FP), AX case, it would load a byte, zero extend it to
32bit and store it in AX.

and yes, the manpage should to be fixed in this case. :)

--
cinap