Bug 1076

Summary: External OPF ISA WG RFC ls016 - DCT/FFT twin-butterfly instructions
Product: Libre-SOC's first SoC Reporter: Luke Kenneth Casson Leighton <lkcl>
Component: SpecificationAssignee: Luke Kenneth Casson Leighton <lkcl>
Status: CONFIRMED ---    
Severity: enhancement CC: konstantinos, libre-soc-isa, programmerjake
Priority: High    
Version: unspecified   
Hardware: PC   
OS: Linux   
URL: https://libre-soc.org/openpower/sv/rfc/ls016/
NLnet milestone: NLnet.2022-08-051.OPF total budget (EUR) for completion of task and all subtasks: 2000
budget (EUR) for this task, excluding subtasks' budget: 2000 parent task for budget allocation: 1009
child tasks for budget allocation: The table of payments (in EUR) for this task; TOML format:
lkcl=2000
Bug Depends on: 1087, 1028, 1074    
Bug Blocks:    

Description Luke Kenneth Casson Leighton 2023-04-29 12:57:43 BST
twin-butterfly instructions for DCT/FFT save a vast number of
instructions for these extremely-common algorithms.
Comment 2 Luke Kenneth Casson Leighton 2023-04-29 14:17:20 BST

    
Comment 3 Luke Kenneth Casson Leighton 2023-04-29 17:32:25 BST
adding c code for core demo of integer DCT twin-butterfly
https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=43da45cab9741fbac58918a9ab730aedcf7438bb

8 instructions to be replaced by one, it's a "no contest"