github-mirrors/neorv32
1
0
Fork 0
mirror of https://github.com/stnolting/neorv32.git synced 2025-04-23 21:57:33 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

[park loop] minor edits

Browse source
This commit is contained in:
stnolting 2023-08-26 08:03:01 +02:00
parent aeacd06f44
commit 2c80402358
1 changed files with 10 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

20
sw/ocd-firmware/park_loop.S
View file

@ -38,7 +38,7 @@
.equ DM_DATA_BASE, 0xffffff80 // base address of debug_module's abstract data buffer (DATA)
.equ DM_SREG_BASE, 0xffffffC0 // base address of debug_module's status register
// status register (SREG) byte(!!!) offsets
// status register (SREG) byte(!) offsets
.equ SREG_HLT_ACK, ( 0 / 8) // -/w: CPU has halted in debug mode and is waiting in park loop
.equ SREG_RES_REQ, ( 8 / 8) // r/-: DM requests to resume
.equ SREG_RES_ACK, ( 8 / 8) // -/w: CPU starts to resume
@ -68,24 +68,24 @@ entry_normal:
// polling loop - waiting for requests
park_loop:
sb zero, (DM_SREG_BASE+SREG_HLT_ACK)(zero) // ACK that CPU is halted
lbu x8, (DM_SREG_BASE+SREG_EXE_REQ)(zero) // request to execute program buffer?
bnez x8, execute
lbu x8, (DM_SREG_BASE+SREG_RES_REQ)(zero) // request to resume?
beqz x8, park_loop
lbu x8, (DM_SREG_BASE+SREG_EXE_REQ)(zero) // request to execute program buffer?
bnez x8, execute
lbu x8, (DM_SREG_BASE+SREG_RES_REQ)(zero) // request to resume?
beqz x8, park_loop
// resume normal operation
resume:
sb x8, (DM_SREG_BASE+SREG_RES_ACK)(zero) // ACK that CPU is about to resume
csrr x8, dscratch0 // restore x8 from dscratch0
sb zero, (DM_SREG_BASE+SREG_RES_ACK)(zero) // ACK that CPU is about to resume
csrr x8, dscratch0 // restore x8 from dscratch0
dret // exit debug mode
// execute program buffer
execute:
sb zero, (DM_SREG_BASE+SREG_EXE_ACK)(zero) // ACK that execution is about to start
csrr x8, dscratch0 // restore x8 from dscratch0
fence.i // synchronize ifetch / i-cache & prefetch with memory (PBUF)
csrr x8, dscratch0 // restore x8 from dscratch0
fence.i // synchronize i-cache and prefetch with memory (PBUF)
jalr zero, zero, %lo(DM_PBUF_BASE) // jump to beginning of program buffer (PBUF)
// fill remaining ROM space with instructions that cause a debug-mode-internal exception
unused:
ecall
ecall // should never be reached