duskos

commit d30ff2622a0817d6ff94d9df7aeeddeef33f61aa
parent dc3754235c32a4155e24836839f9c9ad291ab2bd
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Thu,  1 Jun 2023 20:58:50 -0400

rpi: add 16b support to @!,

This brings us to @! in bootlo.

Also, use immediate modes for LDRH and STRH, which simplifies the code. I simply
hadn't notice its presence yet, I thought I was forced to register-based
offsets.

Diffstat:
M
fs/xcomp/arm/rpi/kernel.fs
 | 
27
++++++++++++++++++---------
M
fs/xcomp/rpiboot.fs
 | 
5
+++++

2 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/fs/xcomp/arm/rpi/kernel.fs b/fs/xcomp/arm/rpi/kernel.fs
@@ -461,16 +461,13 @@ xcode W>A, ( -- )
   ( pc ) r0 pc@>reg, lbldwrite abs>rel b) ,)
 
 \ operand is 16b
-pc mov) r0 rd) 0 i) ,)
 pc to L2 ( operand -- ) \ r0=base instr r1=off
-  orr) r3 rd) r0 rn) $b0 i) ,) \ make into a ldrh/strh op
-  bic) r3 rdn) $04000000 i) ,)
-  ( pc ) r0 pc@>reg,
+  orr) r0 rdn) $b0 i) ,) \ make into a ldrh/strh op
+  bic) r0 rdn) $04000000 i) ,)
+  orr) r0 rdn) $00400000 i) ,) \ immediate
+  \ TODO: support offsets > 0xf
   tst) rTOP rn) $8 i) ,) \ has offset?
-  mov) z) r1 rd) 0 i) ,) \ if not, force a 0
-  orr) r0 rdn) r1 rm) ,)
-  pushret, lbldwrite abs>rel bl) ,) popret, \ copy offset in r0
-  mov) r0 rd) r3 rm) ,)
+  orr) nz) r0 rdn) r1 rm) ,) \ apply immediate offset
   L1 abs>rel b) ,)
 
 pc to L3 ( operand -- ) \ r0=base instr
@@ -483,15 +480,27 @@ pc to L3 ( operand -- ) \ r0=base instr
   L1 abs>rel b) ,)
 
 pc ldr) 0 +i) ,)
-xcode @, ( operand -- )
+xcode @, ( operand -- ) \ Compiled code preserves r0
   ( pc ) r0 pc@>reg, L3 abs>rel b) ,)
 
 pc str) 0 +i) ,)
 xcode !, ( operand -- )
   ( pc ) r0 pc@>reg, L3 abs>rel b) ,)
 
+\ operand is 16b and ARM doesn't have a 16b SWP! LDR+STR+MOV...
+pc mov) rTOP rd) r0 rm) ,)
+pc to L2 ( operand -- )
+  pushret, xdup,
+  bic) rTOP rdn) $f000 i) ,) \ Rd=r0
+  wcall, @, wcall, !,
+  popret,
+  ( pc ) r0 pc@>reg,
+  lbldwrite abs>rel b) ,)
+
 pc swp) rTOP rd) rTOP rm) ,) add) r0 rd) rPSP rn) 0 i) ,)
 xcode @!, pushret, ( operand -- )
+  tst) rTOP rn) $04000000 i) ,)
+  L2 abs>rel b) z) ,)
   dup ( pc ) 4 + r1 pc@>reg,
   lblhbank r0 pc@>reg,
   orr) r0 rdn) r1 rm) ,) \ r0=add instr
diff --git a/fs/xcomp/rpiboot.fs b/fs/xcomp/rpiboot.fs
@@ -32,6 +32,11 @@ code8b 1 W) 8b) [+n], drop, exit,
 code 1-! -1 W) [+n], drop, exit,
 code16b -1 W) 16b) [+n], drop, exit,
 code8b -1 W) 8b) [+n], drop, exit,
+code @! W>A, drop, A) @!, exit,
+code16b HERE @ W>A, drop, A) 16b) @!, exit,
+code8b HERE @ W>A, drop, A) 8b) @!, exit,
+code c@! branch, drop
+code w@! branch, drop
 
 uartinit prompt interactive!