Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Intel Community
- FPGAs and Programmable Solutions
- Intel® Quartus® Prime Software
- LUT mask in arithmetic mode LE

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

wayne

Beginner

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

11-05-2019
09:10 PM

241 Views

LUT mask in arithmetic mode LE

When LE is in arithmetic mode it is not clear how the mask is calculated. In theory, Carry Equation should determine the generation of the carry bit, and Sum Equation determine the bit of the sum. However, in my experience, Sum Equation duplicates the first byte of Carry Equation.

The screenshot shows one of the LE adders.

According to my calculations, the Carry Equation should be

(A&B) # ((A # B) & C) therefore the Carry LUT mask should be E8E8.

However, in the screenshot i see a completely different result.

Link Copied

2 Replies

RichardTanSY_Intel

Employee

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

11-19-2019
08:44 AM

66 Views

Hi, could you try to simulate in Modelsim and check whether the function works or not?

wayne

Beginner

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

11-22-2019
02:26 PM

66 Views

Probably have to do so, but it is strange that there is no detailed information on this problem anywhere.

It’s still not clear why Sum Equation repeats the first bit of Carry Equation

Topic Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

For more complete information about compiler optimizations, see our Optimization Notice.