From 3e11999e62fd860ba5a5419b9fd9a83ccc4ebf0a Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Thu, 22 Aug 2024 03:13:17 +0300
Subject: [PATCH] random number generator, malloc stats

---
 kern/src/libc/malloc.c |   20 +++++++++++++++++++-
 kern/src/libc/malloc.h |    3 +++
 kern/src/libc/rand.c   |   16 ++++++++++++++++
 kern/src/libc/stdlib.h |    5 +++++
 kern/src/main.c        |   34 ++++++++++++++++++++++++++--------
 5 files changed, 69 insertions(+), 9 deletions(-)
 create mode 100644 kern/src/libc/rand.c

diff --git a/kern/src/libc/malloc.c b/kern/src/libc/malloc.c
index d96f7ec..223ba13 100644
--- a/kern/src/libc/malloc.c
+++ b/kern/src/libc/malloc.c
@@ -17,7 +17,8 @@ struct memrange {
 #define RNGEND(rng)	((struct memrange __far*)((char __far*)(rng) + (rng)->len))
 
 static struct memrange __far *pool;
-static unsigned int freemem, num_alloc;
+static unsigned long freemem;
+static unsigned int num_alloc;
 
 
 int kmalloc_init(int numblk)
@@ -161,3 +162,20 @@ void kfree(void __far *p)
 		}
 	}
 }
+
+void dbg_print_kmalloc_pool(void)
+{
+	struct memrange __far *m;
+
+	m = pool;
+	while(m) {
+		printf("[%x:%x/%x] ", FP_SEG(m), FP_OFFS(m), m->len);
+		m = m->next;
+	}
+	putchar('\n');
+}
+
+void dbg_print_kmalloc_stats(void)
+{
+	printf("free memory: %lx, num alloc: %x\n", freemem, num_alloc);
+}
diff --git a/kern/src/libc/malloc.h b/kern/src/libc/malloc.h
index d17a209..facc7a9 100644
--- a/kern/src/libc/malloc.h
+++ b/kern/src/libc/malloc.h
@@ -5,4 +5,7 @@ int kmalloc_init(int numblk);
 void __far *kmalloc(unsigned long sz);
 void kfree(void __far *ptr);
 
+void dbg_print_kmalloc_pool(void);
+void dbg_print_kmalloc_stats(void);
+
 #endif	/* MALLOC_H_ */
diff --git a/kern/src/libc/rand.c b/kern/src/libc/rand.c
new file mode 100644
index 0000000..5eb8103
--- /dev/null
+++ b/kern/src/libc/rand.c
@@ -0,0 +1,16 @@
+#include <stdlib.h>
+#include <inttypes.h>
+
+unsigned long st = 1;
+
+int rand(void)
+{
+	st = st * 1103515245 + 12345;
+    return (unsigned int)(st >> 16) & 0xffff;
+}
+
+void srand(unsigned int seed)
+{
+	st = seed;
+}
+
diff --git a/kern/src/libc/stdlib.h b/kern/src/libc/stdlib.h
index f8ff71b..ec17319 100644
--- a/kern/src/libc/stdlib.h
+++ b/kern/src/libc/stdlib.h
@@ -1,10 +1,15 @@
 #ifndef STDLIB_H_
 #define STDLIB_H_
 
+#define RAND_MAX	32767
+
 #define abs(x)	__builtin_abs(x)
 
 int atoi(const char *str);
 long atol(const char *str);
 long strtol(const char *str, char **endp, int base);
 
+int rand(void);
+void srand(unsigned int seed);
+
 #endif	/* STDLIB_H_ */
diff --git a/kern/src/main.c b/kern/src/main.c
index 178e328..6a412d4 100644
--- a/kern/src/main.c
+++ b/kern/src/main.c
@@ -1,6 +1,7 @@
 #include "config.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <malloc.h>
 #include "intr.h"
 #include "vid.h"
@@ -11,6 +12,8 @@
 
 void kmain(void)
 {
+	int i;
+
 	vid_init();
 	ser_init();
 	con_init();
@@ -18,14 +21,29 @@ void kmain(void)
 
 	printf("eightysix kernel %s\n", VERSTR);
 
-	void __far *ptr = kmalloc(2000);
-	printf("allocated 2k at: %x:%x\n", FP_SEG(ptr), FP_OFFS(ptr));
-	kfree(ptr);
-	printf("freed\n");
-	ptr = kmalloc(256);
-	printf("allocated 256b, got: %x:%x\n", FP_SEG(ptr), FP_OFFS(ptr));
-	ptr = kmalloc(512);
-	printf("allocated 512 more at: %x:%x\n", FP_SEG(ptr), FP_OFFS(ptr));
+	printf("kmalloc free pool\n");
+	dbg_print_kmalloc_pool();
+	printf("kmalloc stats\n");
+	dbg_print_kmalloc_stats();
+
+	void __far *ptr[32];
+
+	for(i=0; i<32; i++) {
+		ptr[i] = kmalloc(256);
+	}
+
+	for(i=0; i<20; i++) {
+		int idx = rand() & 0x1f;
+		if(ptr[idx]) {
+			kfree(ptr[idx]);
+			ptr[idx] = 0;
+		}
+	}
+
+	printf("kmalloc free pool\n");
+	dbg_print_kmalloc_pool();
+	printf("kmalloc stats\n");
+	dbg_print_kmalloc_stats();
 
 	init_intr();
 }
-- 
1.7.10.4