[U-Boot] [PATCH 1/1] disk: part: avoid undefined reference to `__udivmoddi4'

[U-Boot] [PATCH 1/1] disk: part: avoid undefined reference to `__udivmoddi4'

[Heinrich Schuchardt]

When compiling with FTRACE=1 an error

ld.bfd: disk/built-in.o: in function `lba512_muldiv':
disk/part.c:114: undefined reference to `__udivmoddi4

occurred.

Use '>> 11' instead of '/ 2048' to avoid the division.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 disk/part.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/disk/part.c b/disk/part.c
index 98cc54db20..862078f3e7 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -103,17 +103,17 @@ typedef lbaint_t lba512_t;
 #endif

 /*
- * Overflowless variant of (block_count * mul_by / div_by)
+ * Overflowless variant of (block_count * mul_by / 2**div_by)
  * when div_by > mul_by
  */
-static lba512_t lba512_muldiv(lba512_t block_count, lba512_t mul_by, lba512_t div_by)
+static lba512_t lba512_muldiv(lba512_t block_count, lba512_t mul_by, int div_by)
 {
 	lba512_t bc_quot, bc_rem;

 	/* x * m / d == x / d * m + (x % d) * m / d */
-	bc_quot = block_count / div_by;
-	bc_rem  = block_count - div_by * bc_quot;
-	return bc_quot * mul_by + (bc_rem * mul_by) / div_by;
+	bc_quot = block_count >> div_by;
+	bc_rem  = block_count - (bc_quot << div_by);
+	return bc_quot * mul_by + ((bc_rem * mul_by) >> div_by);
 }

 void dev_print (struct blk_desc *dev_desc)
@@ -193,7 +193,7 @@ void dev_print (struct blk_desc *dev_desc)
 		lba512 = (lba * (dev_desc->blksz/512));
 		/* round to 1 digit */
 		/* 2048 = (1024 * 1024) / 512 MB */
-		mb = lba512_muldiv(lba512, 10, 2048);
+		mb = lba512_muldiv(lba512, 10, 11);

 		mb_quot	= mb / 10;
 		mb_rem	= mb - (10 * mb_quot);
--
2.20.1

[U-Boot] [PATCH 1/1] disk: part: avoid undefined reference to `__udivmoddi4'

[Simon Glass]

On Sun, 2 Jun 2019 at 09:36, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
> When compiling with FTRACE=1 an error
>
> ld.bfd: disk/built-in.o: in function `lba512_muldiv':
> disk/part.c:114: undefined reference to `__udivmoddi4
>
> occurred.
>
> Use '>> 11' instead of '/ 2048' to avoid the division.
>
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> ---
>  disk/part.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

Looks OK but I think you should rename div_by to shift_right, or similar.



- SImon

[U-Boot] [PATCH 1/1] disk: part: avoid undefined reference to `__udivmoddi4'

[Heinrich Schuchardt]

On 6/22/19 9:10 PM, Simon Glass wrote:
> On Sun, 2 Jun 2019 at 09:36, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>>
>> When compiling with FTRACE=1 an error
>>
>> ld.bfd: disk/built-in.o: in function `lba512_muldiv':
>> disk/part.c:114: undefined reference to `__udivmoddi4
>>
>> occurred.
>>
>> Use '>> 11' instead of '/ 2048' to avoid the division.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
>> ---
>>   disk/part.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> Looks OK but I think you should rename div_by to shift_right, or similar.

Thanks for reviewing.

The patch is already merged. I will send a new patch to rename the
parameter.

Regards

Heinrcih