From 56dc6ecb70e6fc76d32d6a7194acb273b76bfe0e Mon Sep 17 00:00:00 2001
From: David Guillen Fandos
Date: Mon, 8 Mar 2021 18:44:03 +0100
Subject: Remove libco

This removes libco and all the usages of it (+pthreads).
Rewired all dynarecs and interpreter to return after every frame so that
libretro can process events. This required to make dynarec re-entrant.

Dynarecs were updated to check for new frame on every update (IRQ, cycle
exhaustion, I/O write, etc). The performance impact of doing so should
be minimal (and definitely outweight the libco gains). While at it,
fixed small issues to get a bit more perf: arm dynarec was not idling
correctly, mips was using stack when not needed, etc.

Tested on PSP (mips), OGA (armv7), Linux (x86 and interpreter). Not
tested on Android though.
---
 x86/x86_stub.S | 44 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

(limited to 'x86')

diff --git a/x86/x86_stub.S b/x86/x86_stub.S
index dd98f7a..ba997ba 100644
--- a/x86/x86_stub.S
+++ b/x86/x86_stub.S
@@ -95,6 +95,7 @@
 .equ CPU_MODE,          (29 * 4)
 .equ CPU_HALT_STATE,    (30 * 4)
 .equ CHANGED_PC_STATUS, (31 * 4)
+.equ COMPLETED_FRAME,   (32 * 4)
 
 # destroys ecx and edx
 
@@ -150,6 +151,11 @@ _x86_update_gba:
   call _update_gba            # process the next event
 
   mov %eax, %edi              # edi = new cycle count
+
+  # did we just complete a frame? go back to main then
+  cmpl $0, COMPLETED_FRAME(%ebx)
+  jne return_to_main
+
   # did the PC change?
   cmpl $1, CHANGED_PC_STATUS(%ebx)
   je lookup_pc
@@ -197,6 +203,10 @@ write_epilogue:
 
 alert_loop:
   call _update_gba            # process the next event
+  
+  # did we just complete a frame? go back to main then
+  cmpl $0, COMPLETED_FRAME(%ebx)
+  jne return_to_main
 
   # see if the halt status has changed
   mov CPU_HALT_STATE(%ebx), %edx
@@ -509,24 +519,50 @@ lookup_pc_arm:
 # eax: cycle counter
 
 _execute_arm_translate:
-  movl (_reg), %ebx           # load base register
+  # Save main context, since we need to return gracefully
+  pushl %ebx
+  pushl %esi
+  pushl %edi
+  pushl %ebp
+
+  movl $_reg, %ebx            # load base register
   extract_flags               # load flag variables
   movl %eax, %edi             # load edi cycle counter
 
   movl REG_PC(%ebx), %eax     # load PC
 
+  # (if the CPU is halted, do not start executing but
+  #  loop in the alert loop until it wakes up)
+  cmp $0, CPU_HALT_STATE(%ebx)
+  je 1f
+  call alert_loop     # Need to push something to the stack
+  
+1:
   testl $0x20, REG_CPSR(%ebx)
-  jnz 1f
+  jnz 2f
 
   call _block_lookup_address_arm
   jmp *%eax                   # jump to it
 
-1:
+2:
   call _block_lookup_address_thumb
   jmp *%eax
 
+return_to_main:
+  add $4, %esp             # remove current return addr
+  popl %ebp
+  popl %edi
+  popl %esi
+  popl %ebx
+  ret
+
+.data
+.align 64
+
+_reg:
+  .space 0x100, 0
+
 .comm _memory_map_read 0x8000
 .comm _memory_map_write 0x8000
-.comm _reg 4
 
 
-- 
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