added files

1 files changed, 29 insertions, 0 deletions

diff --git a/lab7bonus_fig4.s b/lab7bonus_fig4.s
new file mode 100644
index 0000000..35e20e0
--- /dev/null
+++ b/lab7bonus_fig4.s
@@ -0,0 +1,29 @@
+    MOV R6,stack_begin
+    LDR R6,[R6]       // initialize stack pointer
+    MOV R4, result    // R4 contains address of result
+    MOV R3,#0
+    STR R3,[R4]       // result = 0;
+    MOV R0,#1         // R0 contains first parameter
+    MOV R1,#5         // R1 contains second parameter
+    MOV R2,#9         // R2 contains third parameter
+    MOV R3,#20        // R3 contains fourth parameter
+    BL  leaf_example  // call leaf_example(1,5,9,20);
+    STR R0,[R4]       // result = leaf_example(1,5,9,20);  
+    HALT
+leaf_example:
+    STR R4,[R6]       // save R4 for use afterwards
+    STR R5,[R6,#-1]   // save R5 for use afterwards
+    ADD R4,R0,R1      // R4 = g + h
+    ADD R5,R2,R3      // R5 = i + j
+    MVN R5,R5         // R5 = ~(i + j)
+    ADD R4,R4,R5      // R4 = (g + h) + ~(i + j)
+    MOV R5,#1
+    ADD R4,R4,R5      // R4 = (g + h) - (i + j)
+    MOV R0,R4         // R0 = return value (g + h) - (i + j) 
+    LDR R5,[R6,#-1]   // restore saved contents of R5
+    LDR R4,[R6]       // restore saved contents of R4
+    BX  R7            // return control to caller
+stack_begin:
+    .word 0xFF
+result:
+    .word 0xCCCC