Re: [PATCH 1/1] efi_loader: printing UEFI revision in helloworld.efi

Hi Heinrich,

On Thu, 1 Sept 2022 at 14:44, Heinrich Schuchardt heinrich.schuchardt@canonical.com wrote:

We need to support multiple digits in the parts of the UEFI verision number. E.g.

EFI_SPECIFICATION_VERSION = (123 << 16) | 456

must be printed as

123.45.6

Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com

lib/efi_loader/helloworld.c | 66 ++++++++++++++++++++++++++++++------- 1 file changed, 54 insertions(+), 12 deletions(-)

Gosh, I'm not sure what to make of this! Could uint2dec() use strtoul()?

Regards, Simon

diff --git a/lib/efi_loader/helloworld.c b/lib/efi_loader/helloworld.c index 10666dc0f2..d565f32745 100644 --- a/lib/efi_loader/helloworld.c +++ b/lib/efi_loader/helloworld.c @@ -29,24 +29,66 @@ static struct efi_system_table *systable; static struct efi_boot_services *boottime; static struct efi_simple_text_output_protocol *con_out;

+/*

• • Print an unsigned 32bit value as decimal number to an u16 string
• • @value: value to be printed
• • @buf: pointer to buffer address

• •         on return position of terminating zero word
    

• */

+static void uint2dec(u32 value, u16 **buf) +{

•   u16 *pos = *buf;
  

•   int i;
  

•   u16 c;
  

•   u64 f;
  

•   /*
  

•    * Increment by .5 and multiply with
  

•    * (2 << 60) / 1,000,000,000 = 0x44B82FA0.9B5A52CC
  

•    * to move the first digit to bit 60-63.
  

•    */
  

•   f = 0x225C17D0;
  

•   f += (0x9B5A52DULL * value) >> 28;
  

•   f += 0x44B82FA0ULL * value;
  

•   for (i = 0; i < 10; ++i) {
  

•           /* Write current digit */
  

•           c = f >> 60;
  

•           if (c || pos != *buf)
  

•                   *pos++ = c + '0';
  

•           /* Eliminate current digit */
  

•           f &= 0xfffffffffffffff;
  

•           /* Get next digit */
  

•           f *= 0xaULL;
  

•   }
  

•   if (pos == *buf)
  

•           *pos++ = '0';
  

•   *pos = 0;
  

•   *buf = pos;
  

+}

/**

• print_uefi_revision() - print UEFI revision number

*/ static void print_uefi_revision(void) {

•   u16 rev[] = u"0.0.0";
  

•   rev[0] = (systable->hdr.revision >> 16) + '0';
  

•   rev[4] = systable->hdr.revision & 0xffff;
  

•   for (; rev[4] >= 10;) {
  

•           rev[4] -= 10;
  

•           ++rev[2];
  

•   u16 rev[13] = {0};
  

•   u16 *buf = rev;
  

•   u16 digit;
  

•   uint2dec(systable->hdr.revision >> 16, &buf);
  

•   *buf++ = '.';
  

•   uint2dec(systable->hdr.revision & 0xffff, &buf);
  

•   /* Minor revision is only to be shown if non-zero */
  

•   digit = *--buf;
  

•   if (digit == '0') {
  

•           *buf = 0;
  

•   } else {
  

•           *buf++ = '.';
  

•           *buf = digit;
    }
  

•   /* Third digit is only to be shown if non-zero */
  

•   if (rev[4])
  

•           rev[4] += '0';
  

•   else
  

•           rev[3] = 0;
  
    con_out->output_string(con_out, u"Running on UEFI ");
    con_out->output_string(con_out, rev);
  

-- 2.37.2