From 867e456de112ee717f430b1a36ac686497fa043d Mon Sep 17 00:00:00 2001
From: Felix Martin <mail@felixm.de>
Date: Tue, 27 Apr 2021 12:47:43 -0400
Subject: [PATCH] Answer 5.46

---
 .gitignore     |  1 +
 ex-5_45-xx.scm | 56 ++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/.gitignore b/.gitignore
index e363ff5..73dbccb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 *.ss#*
 .#*.ss
 
+test.scm
 *.scm~
 *.scm#*
 .#*.scm
diff --git a/ex-5_45-xx.scm b/ex-5_45-xx.scm
index 6ab39b5..c2508b2 100644
--- a/ex-5_45-xx.scm
+++ b/ex-5_45-xx.scm
@@ -2,7 +2,6 @@
 (load "shared/sicp-load-eceval-compiler")
 (load "shared/sicp-compiler")
 
-
 (display "\nex-5.45 - factorial-stack-usage-comparison\n")
 
 ;(compile-and-go
@@ -35,9 +34,62 @@
 
 ; b. Use special handling for primitive procedures from exercise 5.38.
 
-(display "[answered]\n")
+(display "[done]\n")
 
 (display "\nex-5.46 - fibo-stack-usage-comparison\n")
 
+;(compile-and-go
+; '(begin
+;    (define (fib n)
+;      (if (< n 2)
+;          n
+;          (+ (fib (- n 1)) (fib (- n 2)))))
+;    (fib 10)))
+
+; | (fib 10)       | pushes | depth  |
+; | -------------- | ------ | ------ |
+; | machine        |    264 |     18 |
+; | compiled       |    882 |     29 |
+; | evaluator      |   4950 |     53 |
+
+; | (fib 20)       | pushes | depth  |
+; | -------------- | ------ | ------ |
+; | machine        |  32835 |     38 |
+; | compiled       | 109452 |     59 |
+; | evaluator      | 612942 |    103 |
+
+(display "[done]\n")
 
 (display "\nex-5.47\n")
+
+; Exercise 5.47.  This section described how to modify the explicit-control
+; evaluator so that interpreted code can call compiled procedures. Show how to
+; modify the compiler so that compiled procedures can call not only primitive
+; procedures and compiled procedures, but interpreted procedures as well. This
+; requires modifying compile-procedure-call to handle the case of compound
+; (interpreted) procedures. Be sure to handle all the same target and linkage
+; combinations as in compile-proc-appl. To do the actual procedure application,
+; the code needs to jump to the evaluator's compound-apply entry point. This
+; label cannot be directly referenced in object code (since the assembler
+; requires that all labels referenced by the code it is assembling be defined
+; there), so we will add a register called compapp to the evaluator machine to
+; hold this entry point, and add an instruction to initialize it:
+
+;  (assign compapp (label compound-apply))
+;  (branch (label external-entry))      ; branches if flag is set
+;read-eval-print-loop
+;  ...
+
+; To test your code, start by defining a procedure f that calls a procedure g.
+; Use compile-and-go to compile the definition of f and start the evaluator.
+; Now, typing at the evaluator, define g and try to call f.
+
+
+(compile-and-go
+  '(define (f n)
+     (g n)))
+
+(display "\nex-5.48\n")
+
+; (display "\nex-5.49\n")
+