Implement INC instructions and fix add/sub/mul behaviour

2 files changed, 34 insertions, 18 deletions

diff --git a/src/main.c b/src/main.c
index 315292e..f70fbe9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -43,7 +43,7 @@ void
 init_uxn() {
     // Initialize uxn.
     u32 fill = 0;
-    dma_fill(uxn_ram, fill, 0x10300, 3);
+    dma_fill(uxn_ram, fill, sizeof(uxn_ram), 3);
     // uxn_boot(u, uxn_ram, uxn_dei, uxn_deo);
 
     // Copy rom to VM.
@@ -52,13 +52,20 @@ init_uxn() {
         // ADD test.
         0x80, 0x04, 0x80, 0x08, 0x18,             // #04 #08 ADD      -> 0c
         0xa0, 0x00, 0x04, 0xa0, 0x00, 0x08, 0x38, // #0004 #0008 ADD2 -> 000c
+        0xa0, 0x00, 0xff, 0xa0, 0x00, 0x02, 0x38, // #00ff #0002 ADD2 -> 0101
         // SUB test.
-        0x80, 0x08, 0x80, 0x03, 0x19,             // #08 #03 ADD      -> 05
-        0xa0, 0x00, 0x08, 0xa0, 0x00, 0x03, 0x39, // #0008 #0003 ADD2 -> 0005
+        0x80, 0x08, 0x80, 0x03, 0x19,             // #08 #03 SUB      -> 05
+        0xa0, 0x00, 0x08, 0xa0, 0x00, 0x03, 0x39, // #0008 #0003 SUB2 -> 0005
+        0xa0, 0x01, 0x01, 0xa0, 0x00, 0x02, 0x39, // #0008 #0003 SUB2 -> 00ff
         // MUL test.
         0x80, 0x03, 0x80, 0x04, 0x1a,             // #03 #04 MUL      -> 0c
         0xa0, 0x00, 0x03, 0xa0, 0x00, 0x04, 0x3a, // #0003 #0004 MUL2 -> 000c
         0xa0, 0x00, 0xff, 0xa0, 0x00, 0x02, 0x3a, // #00ff #0002 MUL2 -> 01fe
+        // INC test.
+        0x80, 0x09, 0x01,                         // #09 INC          -> 0a
+        0xa0, 0x00, 0x09, 0x21,                   // #0009 INC2       -> 000a
+        0xa0, 0x00, 0xff, 0x21,                   // #0009 INC2       -> 0100
+        0xa0, 0x00, 0xff, 0x21, 0x21              // #0009 INC2 INC2  -> 0101
     };
     memcpy(uxn_ram + PAGE_PROGRAM, uxn_rom, sizeof(uxn_rom));
 }
diff --git a/src/uxn-core.s b/src/uxn-core.s
index e35707f..95afc1a 100644
--- a/src/uxn-core.s
+++ b/src/uxn-core.s
@@ -79,9 +79,19 @@ lit2r:
     b       uxn_decode
 
 inc:
+    ldrb    r3, [r1, #-1]!
+    add     r3, #1
+    strb    r3, [r1], #1
     b       uxn_decode
 
 inc2:
+    ldrb    r3, [r1, #-1]!
+    ldrb    r5, [r1, #-1]!
+    orr     r3, r3, r5, lsl #8
+    add     r3, r3, #1
+    strb    r3, [r1, #1]
+    lsr     r3, #8
+    strb    r3, [r1], #2
     b       uxn_decode
 
 pop:
@@ -226,14 +236,14 @@ add:
 add2:
     ldrb    r3, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r3, r5, r3, lsl #8
+    orr     r3, r3, r5, lsl #8
     ldrb    r4, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r4, r5, r4, lsl #8
+    orr     r4, r4, r5, lsl #8
     add     r3, r3, r4
-    strb    r3, [r1], #1
+    strb    r3, [r1, #1]
     lsr     r3, #8
-    strb    r3, [r1], #1
+    strb    r3, [r1], #2
     b       uxn_decode
 
 sub:
@@ -246,14 +256,14 @@ sub:
 sub2:
     ldrb    r3, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r3, r5, r3, lsl #8
+    orr     r3, r3, r5, lsl #8
     ldrb    r4, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r4, r5, r4, lsl #8
+    orr     r4, r4, r5, lsl #8
     sub     r3, r4, r3
-    strb    r3, [r1], #1
+    strb    r3, [r1, #1]
     lsr     r3, #8
-    strb    r3, [r1], #1
+    strb    r3, [r1], #2
     b       uxn_decode
 
 mul:
@@ -266,15 +276,14 @@ mul:
 mul2:
     ldrb    r3, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r3, r5, r3, lsl #8
+    orr     r3, r3, r5, lsl #8
     ldrb    r4, [r1, #-1]!
     ldrb    r5, [r1, #-1]!
-    orr     r4, r5, r4, lsl #8
-    mul     r5, r3, r4
-    lsr     r3, r5, #24
-    strb    r3, [r1], #1
-    lsr     r5, #16
-    strb    r5, [r1], #1
+    orr     r4, r4, r5, lsl #8
+    mul     r3, r3, r4
+    strb    r3, [r1, #1]
+    lsr     r3, #8
+    strb    r3, [r1], #2
     b       uxn_decode
 
 div: