From f1b128baeb5a8ab1ae1683a395b180d4cb113fb4 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Mon, 11 Feb 2019 20:46:06 +0100
Subject: [PATCH] Signed comparisons now work correctly; sadly, Star Trek
 increases from 39656 to 39726 bytes. Note that the emulator doesn't set P/V
 correctly and all the tests fail. Testing in z80ex works fine.

---
 mach/i80/libem/rst.s | 12 +++++++++++-
 mach/i80/ncg/table   | 18 +++++++++++++++---
 mach/i80/top/table   |  3 ++-
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/mach/i80/libem/rst.s b/mach/i80/libem/rst.s
index 7bf6ade29..2e13584e5 100644
--- a/mach/i80/libem/rst.s
+++ b/mach/i80/libem/rst.s
@@ -17,6 +17,11 @@
     shld 0x11
     lxi h, rst3
     shld 0x19
+
+    lhld rst4
+    shld 0x20
+    lhld rst4+2
+    shld 0x22
     ret
 
     ! de = [bc+const1] (remember bc is the frame pointer)
@@ -69,4 +74,9 @@ rst3:
 
     dad b
     ret
-    
\ No newline at end of file
+    
+    ! Adjust flags for signed comparison
+rst4:
+    rpo
+    xri 0x80
+    ret
diff --git a/mach/i80/ncg/table b/mach/i80/ncg/table
index 00587bcbf..963a1f07f 100644
--- a/mach/i80/ncg/table
+++ b/mach/i80/ncg/table
@@ -13,6 +13,12 @@ EM_WSIZE = 2
 EM_PSIZE = 2
 EM_BSIZE = 4
 
+#ifdef USE_I80_RSTS
+   #define SIGN_ADJUST rst {const1, 4}
+#else
+   #define SIGN_ADJUST jpo {label, 1f} xri {const1, 0x80} 1:
+#endif
+
 SL=4
 
 PROPERTIES
@@ -103,7 +109,7 @@ INSTRUCTIONS
    jnz	label:ro			cost(3,10).
    jp	label:ro			cost(3,10).
 /* jpe	label:ro			cost(3,10).	*/
-/* jpo	label:ro			cost(3,10).	*/
+   jpo	label:ro			cost(3,10).
    jz	label:ro			cost(3,10).
    lda	label:ro 	kills a		cost(3,13).
    ldax	regind:ro 	kills a		cost(1, 7).
@@ -1860,6 +1866,7 @@ pat blt
          sui {const1, %1.num & 0xff}
          mov a, %2.1
          sbi {const1, %1.num >> 8}
+         SIGN_ADJUST
          jm {label, $1}
    with hl_or_de const2 STACK
       uses areg
@@ -1868,14 +1875,16 @@ pat blt
          sub %1.2
          mvi a, {const1, %2.num >> 8}
          sbb %1.1
+         SIGN_ADJUST
          jm {label, $1}
    with hl_or_de hl_or_de STACK
       uses areg
       gen
-         mov a,%2.2
+         mov a, %2.2
          sub %1.2
-         mov a,%2.1
+         mov a, %2.1
          sbb %1.1
+         SIGN_ADJUST
          jm {label,$1}
 
 pat bgt
@@ -1891,6 +1900,7 @@ pat bge
          sui {const1, %1.num & 0xff}
          mov a, %2.1
          sbi {const1, %1.num >> 8}
+         SIGN_ADJUST
          jp {label, $1}
    with hl_or_de const2 STACK
       uses areg
@@ -1899,6 +1909,7 @@ pat bge
          sub %1.2
          mvi a, {const1, %2.num >> 8}
          sbb %1.1
+         SIGN_ADJUST
          jp {label, $1}
    with hl_or_de hl_or_de STACK
       uses areg
@@ -1907,6 +1918,7 @@ pat bge
          sub %1.2
          mov a,%2.1
          sbb %1.1
+         SIGN_ADJUST
          jp {label,$1}
 
 pat ble
diff --git a/mach/i80/top/table b/mach/i80/top/table
index e77100735..9ff98a330 100644
--- a/mach/i80/top/table
+++ b/mach/i80/top/table
@@ -1,5 +1,5 @@
 
-/* 68020 desciptor table for ACK target optimizer */
+/* 8080 desciptor table for ACK target optimizer */
 
 MAXOP 2;
 
@@ -14,5 +14,6 @@ xchg : inx h : xchg          -> inx d ;
 xchg : inx d : xchg          -> inx h ;
 
 cpi 0                        -> ora a ;
+call X : ret                 -> jmp X ;
 
 %%;