[PATCH v5 8/8] lib: sbi: Speed-up sbi_printf() and friends using nputs()

[Anup Patel]

On Wed, Feb 1, 2023 at 2:52 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> On Fri, Jan 13, 2023 at 05:11:10PM +0530, Anup Patel wrote:
> > The sbi_printf() is slow for semihosting because it prints one
> > character at a time. To speed-up sbi_printf() for semihosting,
> > we use a temporary buffer and nputs().
> >
> > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > ---
> >  lib/sbi/sbi_console.c | 52 ++++++++++++++++++++++++++++---------------
> >  1 file changed, 34 insertions(+), 18 deletions(-)
> >
> > diff --git a/lib/sbi/sbi_console.c b/lib/sbi/sbi_console.c
> > index c1b9f73..41881d7 100644
> > --- a/lib/sbi/sbi_console.c
> > +++ b/lib/sbi/sbi_console.c
> > @@ -42,31 +42,29 @@ void sbi_putc(char ch)
> >       }
> >  }
> >
> > -void sbi_puts(const char *str)
> > +static void nputs(const char *str, unsigned long len)
> >  {
> > -     spin_lock(&console_out_lock);
> > +     unsigned long i;
> > +
> >       if (console_dev && console_dev->console_puts) {
> > -             console_dev->console_puts(str, sbi_strlen(str));
> > +             console_dev->console_puts(str, len);
> >       } else {
> > -             while (*str) {
> > -                     sbi_putc(*str);
> > -                     str++;
> > -             }
> > +             for (i = 0; i < len; i++)
> > +                     sbi_putc(str[i]);
> >       }
> > +}
> > +
> > +void sbi_puts(const char *str)
> > +{
> > +     spin_lock(&console_out_lock);
> > +     nputs(str, sbi_strlen(str));
> >       spin_unlock(&console_out_lock);
> >  }
> >
> >  void sbi_nputs(const char *str, unsigned long len)
> >  {
> > -     unsigned long i;
> > -
> >       spin_lock(&console_out_lock);
> > -     if (console_dev && console_dev->console_puts) {
> > -             console_dev->console_puts(str, len);
> > -     } else {
> > -             for (i = 0; i < len; i++)
> > -                     sbi_putc(str[i]);
> > -     }
> > +     nputs(str, len);
> >       spin_unlock(&console_out_lock);
> >  }
> >
> > @@ -102,6 +100,7 @@ unsigned long sbi_ngets(char *str, unsigned long len)
> >  #define PAD_ZERO 2
> >  #define PAD_ALTERNATE 4
> >  #define PRINT_BUF_LEN 64
> > +#define PRINT_TBUF_MAX 128
> >
> >  #define va_start(v, l) __builtin_va_start((v), l)
> >  #define va_end __builtin_va_end
> > @@ -217,12 +216,26 @@ static int printi(char **out, u32 *out_len, long long i, int b, int sg,
> >
> >  static int print(char **out, u32 *out_len, const char *format, va_list args)
> >  {
> > -     int width, flags;
> > -     int pc = 0;
> > -     char scr[2];
> > +     u32 tbuf_len;
> > +     int width, flags, pc = 0;
> > +     char scr[2], *tout, tbuf[PRINT_TBUF_MAX];
> > +     bool use_tbuf = (!out) ? true : false;
>
> print() is only called with a non-null 'out' parameter or under
> console_out_lock, so we can use global variable for the buffer
> to avoid putting it on the stack, and it can be larger.

Okay, I will update.

>
> >       unsigned long long tmp;
> >
> > +     if (use_tbuf) {
> > +             tbuf_len = PRINT_TBUF_MAX;
> > +             tout = tbuf;
> > +             out = &tout;
> > +             out_len = &tbuf_len;
> > +     }
> > +
> >       for (; *format != 0; ++format) {
> > +             if (use_tbuf && !tbuf_len) {
> > +                     nputs(tbuf, PRINT_TBUF_MAX);
> > +                     tbuf_len = PRINT_TBUF_MAX;
> > +                     tout = tbuf;
> > +             }
> > +
> >               if (*format == '%') {
> >                       ++format;
> >                       width = flags = 0;
> > @@ -348,6 +361,9 @@ literal:
> >               }
> >       }
> >
> > +     if (use_tbuf && tbuf_len < PRINT_TBUF_MAX)
> > +             nputs(tbuf, PRINT_TBUF_MAX - tbuf_len);
> > +
> >       return pc;
> >  }
> >
> > --
> > 2.34.1
> >
>
> Otherwise,
>
> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
>
> Thanks,
> drew

Regards,
Anup