From 1c6dc303b83de5b7c86037050d12c30c20bae18b Mon Sep 17 00:00:00 2001
From: Bryan McShea <cat71602@gmail.com>
Date: Tue, 11 Oct 2022 21:02:17 -0400
Subject: [PATCH] ok I need to actually do school work

---
 src/lib/heap.s  | 39 ++++++++++++++++---------------
 src/lib/str.s   |  3 +--
 src/test/heap.s | 62 ++++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 74 insertions(+), 30 deletions(-)

diff --git a/src/lib/heap.s b/src/lib/heap.s
index 8ae1e5c..34967b0 100644
--- a/src/lib/heap.s
+++ b/src/lib/heap.s
@@ -7,7 +7,7 @@
 .equ align_imask,   0b111
 .equ align_mask,    ~align_imask
 
-.equ used_mask,     0b001
+.equ prev_used,     0b001
 .equ size_mask,     align_mask
 
 # block node
@@ -36,14 +36,16 @@ heap_oom:
 .section .data
 
 .align 4
-.equ heap_start, 0
-.equ heap_first_free, 8 # matches fb_next
-.equ heap_end, 16
-.global heap_info       # for testing only
+.global heap_info           # global for testing only
+.equ heap_last_used,    0   # last free block will set this
+.equ heap_first_free,   8   # matches fb_next
+.equ heap_start,        16
+.equ heap_end,          24
 heap_info:
-    .dword __global_pointer$
     .dword 0
     .dword 0
+    .dword __global_pointer$
+    .dword 0
 
 
 
@@ -72,23 +74,23 @@ heap_init:
     li      a0, 0
     jal     brk
     andi    a0, a0, align_mask
-    sub     t2, a0, t1      # size = end - start (t2)
+    sub     t2, a0, t1          # size = end - start (t2)
     li      t3, sizeof_fb
-    bgeu    t2, t3, 0f      # check if enough mem to start
+    bgeu    t2, t3, 0f          # check if enough mem to start
 
     move    a1, a0
     add     a0, t1, t3
-    jal     brk_or_panic    # if not, get more
-    sub     t2, a0, t1      # recalc size (t2)
+    jal     brk_or_panic        # if not, get more
+    sub     t2, a0, t1          # recalc size (t2)
 0:
     sd      a0, heap_end(t0)
 
     # create initial free block
 
-    ori     t2, t2, 0x1     # add prev used
-    sd      t2, bsize(t1)   # store size
-    sd      t0, fb_next(t1) # store next
-    sd      t1, -8(a0)      # store addr at end
+    ori     t2, t2, prev_used   # add prev used
+    sd      t2, bsize(t1)       # store size
+    sd      t0, fb_next(t1)     # store next
+    sd      t1, -8(a0)          # store addr at end
 
     sd      t1, heap_first_free(t0)
 
@@ -149,10 +151,9 @@ heap_alloc:
     jal     brk_or_panic        # set heap end (a0)
     sd      a0, heap_end(t3)    # update end in info
     sub     t2, a0, t1          # new free space (t2)
-    andi    t5, t2, 1           # prev used bit
+    andi    t5, t2, prev_used   # prev used bit
     sd      t5, bsize(t1)       # update size
     sd      t3, fb_next(t1)     # update next (for case 3)
-
 0:
 
     # deal with extra free space
@@ -165,7 +166,7 @@ heap_alloc:
     sd      t3, fb_next(t6)     # set prev block next to new
     add     t6, t3, t5          # store addr at end
     sd      t3, -8(t6)
-    ori     t6, t5, 1           # store size with prev in use
+    ori     t6, t5, prev_used   # store size with prev in use
     sd      t6, bsize(t3)
     ld      t6, fb_next(t1)     # copy next
     sd      t6, fb_next(t3)
@@ -178,14 +179,14 @@ heap_alloc:
     add     t3, t1, t0
     beq     t3, t4, 1f          # if this is not at the end
     ld      t4, bsize(t3)       # set next's prev used to 1
-    ori     t4, t4, 1
+    ori     t4, t4, prev_used
     sd      t4, bsize(t3)
 1:
 
     # create used block
 
     add     t2, t0, t1          # end of block
-    ori     t0, t0, 1           # prev used bit
+    ori     t0, t0, prev_used   # prev used bit
     sd      t0, bsize(t1)       # store size
     sd      zero, fb_next(t1)   # remove free block stuff
     sd      zero, -8(t2)
diff --git a/src/lib/str.s b/src/lib/str.s
index b412e10..ee4b66c 100644
--- a/src/lib/str.s
+++ b/src/lib/str.s
@@ -27,11 +27,10 @@ strlen:
 strcpy:
 0:
     lb      t0, (a1)
-    beqz    t0, 0f
     sb      t0, (a0)
+    beqz    t0, 0f
     addi    a0, a0, 1
     addi    a1, a1, 1
     j       0b
 0:
-    sb      t0, (a0)
     ret
diff --git a/src/test/heap.s b/src/test/heap.s
index 3b4ccc8..8fc6b81 100644
--- a/src/test/heap.s
+++ b/src/test/heap.s
@@ -1,13 +1,18 @@
 .section .rodata
 
-.word 0f - print_msg
-print_msg:
-    .string "Current heap:"
+.word 0f - hinfo_msg
+hinfo_msg:
+    .string "Current heap info:"
+0:
+
+.word 0f - block_msg
+block_msg:
+    .string "Current heap blocks:"
 0:
 
 .word 0f - dots
 dots:
-    .string "................"
+    .string "..."
 0:
 
 .word 0f - hexstr
@@ -73,19 +78,57 @@ heap_test:
     ret
 
 print_heap:
-    addi    sp, sp, -(3*8)
+    addi    sp, sp, -(4*8)
     sd      ra, 0(sp)
     sd      s0, 8(sp)
     sd      s1, 16(sp)
+    sd      s2, 24(sp)
 
-    la      a0, print_msg
+    # info
+
+    la      a0, hinfo_msg
+    lw      a1, -4(a0)
+    jal     print
+    jal     print_space
+
+    la      a0, hexstr
+    lw      a1, -4(a0)
+    jal     print
+
+    la      s0, heap_info
+    move    a0, s0
+    jal     print_hex
+    jal     printnl
+
+    li      s1, 0
+    li      s2, 4
+0:
+    beq     s1, s2, 0f
+    jal     print_space
+    jal     print_space
+    li      t1, 8
+    mul     t0, s1, t1
+    add     t0, s0, t0
+    ld      a0, 0(t0)
+    jal     print_hex
+    jal     printnl
+    addi    s1, s1, 1
+    j       0b
+0:
+
+    # blocks
+
+    la      a0, block_msg
     lw      a1, -4(a0)
     jal     println
 
     la      t0, heap_info
-    ld      s0, 0(t0)
-    ld      s1, 16(t0)
+    ld      s0, 16(t0)
+    ld      s1, 24(t0)
 0:
+    jal     print_space
+    jal     print_space
+
     la      a0, hexstr
     lw      a1, -4(a0)
     jal     print
@@ -121,5 +164,6 @@ print_heap:
     ld      ra, 0(sp)
     ld      s0, 8(sp)
     ld      s1, 16(sp)
-    addi    sp, sp, +(3*8)
+    ld      s2, 24(sp)
+    addi    sp, sp, +(4*8)
     ret