Bug 334 - POWER decode A=zero needs to be set as a flag in Execute1Type
Summary: POWER decode A=zero needs to be set as a flag in Execute1Type
Status: RESOLVED FIXED
Alias: None
Product: Libre-SOC's first SoC
Classification: Unclassified
Component: Source Code (show other bugs)
Version: unspecified
Hardware: Other Linux
: --- enhancement
Assignee: Luke Kenneth Casson Leighton
URL:
Depends on:
Blocks: 336 305
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Reported: 2020-05-21 02:57 BST by Luke Kenneth Casson Leighton
Modified: 2020-06-30 16:49 BST (History)
1 user (show)

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Description Luke Kenneth Casson Leighton 2020-05-21 02:57:16 BST 
https://git.libre-soc.org/?p=soc.git;a=blob;f=src/soc/decoder/power_decoder2.py;h=3b9beba954a2f0f7ebefc7a731d8eddcb3705698;hb=HEAD

detection of zero RA reg (src1) needs to be passed through the pipelines (via the CompUnits - see bug 336) just like B (src2) being used as an immediate.

this therefore needs to be done in the pipeline unit tests (test_pipe_caller.py), qemu to check the simulation, then HDL unit tests detect RA_OR_ZERO and likewise set A to zero.

a flag "a_is_zero" or such would be set in power_decode2 in the execute phase.
Comment 1 Luke Kenneth Casson Leighton 2020-05-21 17:48:51 BST 
added the flag,
https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=e0088f72dbd8b53acc587fa2ec2fb9fa4aeb17c5

commit 65aceac3fa2cdc1bc34120551c23a9dff681c02e (HEAD -> master, origin/master)
Author: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date:   Thu May 21 17:48:20 2020 +0100

    add zero_a flag to CompALUOpSubset

commit e0088f72dbd8b53acc587fa2ec2fb9fa4aeb17c5
Author: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date:   Thu May 21 17:44:21 2020 +0100

    add zero_a flag to Decode2ExecuteType