From 105cf743ff8b77c72d9602c144e052eff4b0fd24 Mon Sep 17 00:00:00 2001
From: Danny Milosavljevic <dannym@scratchpost.org>
Date: Thu, 11 Apr 2019 19:58:08 +0200
Subject: [PATCH] ARM: Support negative values as immediate.

* lib/arm-mes/arm.M1 (mvn____%r0,$i8): New macro.
(mvn____%r1,$i8): New macro.
(mvn____%r7,$i8): New macro.
* module/mescc/armv4/as.scm (immediate->r0): Use it.
(armv4:value->r): Use it.
---
 lib/arm-mes/arm.M1        | 5 +++++
 module/mescc/armv4/as.scm | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/arm-mes/arm.M1 b/lib/arm-mes/arm.M1
index e9347a65..0cb1ed6c 100644
--- a/lib/arm-mes/arm.M1
+++ b/lib/arm-mes/arm.M1
@@ -95,6 +95,11 @@ DEFINE jne 1a
 DEFINE mov____$i8,%r0 00a0e3
 DEFINE mov____$i8,%r1 10a0e3 # mov     r1, #66
 DEFINE mov____$i8,%r7 70a0e3
+
+DEFINE mvn____%r0,$i8 00e0e3
+DEFINE mvn____%r1,$i8 10e0e3
+DEFINE mvn____%r7,$i8 70e0e3
+
 DEFINE mov____%r0,%r1 0010a0e1
 DEFINE mov____%r0,%r2 0020a0e1
 DEFINE mov____%r0,(%r1) 000081e5
diff --git a/module/mescc/armv4/as.scm b/module/mescc/armv4/as.scm
index 457b9297..357384a4 100644
--- a/module/mescc/armv4/as.scm
+++ b/module/mescc/armv4/as.scm
@@ -48,12 +48,16 @@
 
 (define (immediate->r0 v)
   (if (< (abs v) #x80)
-     `(((#:immediate1 ,v) "mov____$i8,%r0"))
+      (if (< v 0)
+         `(((#:immediate1 ,(- -1 v)) "mvn____%r0,$i8"))
+         `(((#:immediate1 ,v) "mov____$i8,%r0")))
      `(("mov____$i32,%r0" (#:immediate ,v)))))
 
 (define (armv4:value->r info v)
   (let ((r (get-r info)))
-    `(((#:immediate1 ,v) ,(string-append "mov____$i8,%" r)))))
+    (if (< v 0)
+       `(((#:immediate1 ,(- -1 v)) ,(string-append "mvn____%" r ",$i8")))
+       `(((#:immediate1 ,v) ,(string-append "mov____$i8,%" r))))))
 
 (define (armv4:ret . rest)
   "Note: Pretends to be on x86 a lot"