From 3b69ce8cfbb19db431523f7221c43610e8287861 Mon Sep 17 00:00:00 2001
From: Sean Lachhander <slachhander@albany.edu>
Date: Wed, 26 Apr 2017 11:04:02 -0400
Subject: [PATCH 1/2] Add files via upload

---
 README.md     |   2 +-
 c_to_nasm.sh  |  21 +++++++
 constants.inc |  29 ++++++++++
 devfs.c       | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++
 devfs.h       |  10 ++++
 devfs.o       | Bin 0 -> 3036 bytes
 fb.o          | Bin 4316 -> 4432 bytes
 gdt.h         |   1 +
 gdt_asm.o     | Bin 0 -> 608 bytes
 gdt_asm.s     |  27 +++++++++
 idt.c         |   3 +-
 idt.o         | Bin 3624 -> 4188 bytes
 interrupt.c   |   6 +-
 interrupt.o   | Bin 1400 -> 1532 bytes
 14 files changed, 240 insertions(+), 7 deletions(-)
 create mode 100644 c_to_nasm.sh
 create mode 100644 constants.inc
 create mode 100644 devfs.c
 create mode 100644 devfs.h
 create mode 100644 devfs.o
 create mode 100644 gdt_asm.o
 create mode 100644 gdt_asm.s

diff --git a/README.md b/README.md
index fa9230f..33f75d8 100755
--- a/README.md
+++ b/README.md
@@ -1 +1 @@
-# LittleOS# OS
+# LittleOS
\ No newline at end of file
diff --git a/c_to_nasm.sh b/c_to_nasm.sh
new file mode 100644
index 0000000..37b9e7a
--- /dev/null
+++ b/c_to_nasm.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# Translates a C header to a NASM header
+# The C header can only make use of:
+#   - #define
+#   - #ifndef
+#   - #endif
+
+# INPUT: A list of the required NASM headers
+
+set -e
+
+for NASM_HEADER in $@
+do
+    C_HEADER="${NASM_HEADER%%.inc}.h"
+    if [ $C_HEADER -nt $NASM_HEADER ]; then
+        sed 's/\/\*/;/' $C_HEADER | # change start of comments
+        sed 's/\*\///'            | # change end of comments
+        sed 's/^#/%/'             > $NASM_HEADER
+    fi
+done
diff --git a/constants.inc b/constants.inc
new file mode 100644
index 0000000..93728b3
--- /dev/null
+++ b/constants.inc
@@ -0,0 +1,29 @@
+%ifndef CONSTANTS_H
+%define CONSTANTS_H
+
+; numeric contants 
+%define FOUR_KB     0x1000
+%define ONE_MB      0x100000
+%define FOUR_MB     0x400000
+%define EIGHT_MB    0x800000
+
+; virtual memory 
+%define KERNEL_START_VADDR  0xC0000000
+%define KERNEL_PDT_IDX      (KERNEL_START_VADDR >> 22)
+
+; kernel stack 
+%define KERNEL_STACK_SIZE FOUR_KB
+
+; interrupts 
+%define SYSCALL_INT_IDX 0xAE
+
+; segements 
+%define SEGSEL_KERNEL_CS 0x08
+%define SEGSEL_KERNEL_DS 0x10
+%define SEGSEL_USER_SPACE_CS 0x18
+%define SEGSEL_USER_SPACE_DS 0x20
+
+; registers 
+%define REG_EFLAGS_DEFAULT 0x202
+
+%endif
diff --git a/devfs.c b/devfs.c
new file mode 100644
index 0000000..9ea282b
--- /dev/null
+++ b/devfs.c
@@ -0,0 +1,148 @@
+#include "devfs.h"
+#include "common.h"
+#include "kmalloc.h"
+#include "log.h"
+#include "string.h"
+
+struct devfs_inode {
+    struct devfs_inode *next;
+    char const *name;
+    vnode_t *node;
+};
+typedef struct devfs_inode devfs_inode_t;
+
+static devfs_inode_t *devices = NULL;
+
+static vnode_t root;
+static vnodeops_t vnodeops;
+static vfsops_t vfsops;
+
+static int devfs_root(vfs_t *vfs, vnode_t *out)
+{
+    UNUSED_ARGUMENT(vfs);
+
+    out->v_op = root.v_op;
+    out->v_data = root.v_data;
+
+    return 0;
+}
+
+static int devfs_open(vnode_t *n)
+{
+    UNUSED_ARGUMENT(n);
+
+    return -1;
+}
+static int devfs_read(vnode_t *node, void *buf, uint32_t count)
+{
+    UNUSED_ARGUMENT(node);
+    UNUSED_ARGUMENT(buf);
+    UNUSED_ARGUMENT(count);
+
+    return -1;
+}
+
+static int devfs_write(vnode_t *n, char const *s, size_t l)
+{
+    UNUSED_ARGUMENT(n);
+    UNUSED_ARGUMENT(s);
+    UNUSED_ARGUMENT(l);
+
+    return -1;
+}
+
+static int devfs_getattr(vnode_t *n, vattr_t *attr)
+{
+    UNUSED_ARGUMENT(n);
+
+    attr->file_size = 0;
+
+    return 0;
+}
+
+static int devfs_lookup(vnode_t *dir, char const *name, vnode_t *out)
+{
+    UNUSED_ARGUMENT(dir);
+
+    if (name == NULL) {
+        log_error("devfs_lookup",
+                  "Trying to lookup a null path\n");
+        return -1;
+    }
+
+    devfs_inode_t *i;
+    for (i = devices; i != NULL; i = i->next) {
+        if (strcmp(i->name, name) == 0) {
+            out->v_op = i->node->v_op;
+            out->v_data = i->node->v_data;
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
+int devfs_add_device(char const *path, vnode_t *node)
+{
+    if (path == NULL || strlen(path) == 0) {
+        log_error("devfs_add_device",
+                  "path is empty or NULL\n");
+        return -1;
+    }
+
+    devfs_inode_t *i;
+    for (i = devices; i != NULL; i = i->next) {
+        if (strcmp(i->name, path) == 0) {
+            log_error("devfs_add_device",
+                      "Trying to add a device that is already added: %s\n",
+                      path);
+            return -1;
+        }
+    }
+
+    int len = strlen(path) + 1;
+    char *copy = kmalloc(len);
+    if (copy == NULL) {
+        log_error("devfs_add_device",
+                  "Could not allocated memory for path name %s\n",
+                  path);
+        return -1;
+    }
+    memcpy(copy, path, len);
+
+    devfs_inode_t *inode = kmalloc(sizeof(devfs_inode_t));
+    if (inode == NULL) {
+        log_error("devfs_add_device",
+                  "Could not allocated memory for devfs_inode_t struct\n");
+        kfree(copy);
+        return -1;
+    }
+
+    inode->next = NULL;
+    inode->name = copy;
+    inode->node = node;
+
+    if (devices == NULL) {
+        devices = inode;
+    } else {
+        devices->next = inode;
+    }
+
+    return 0;
+}
+
+int devfs_init(vfs_t *vfs)
+{
+    vnodeops.vn_open = &devfs_open;
+    vnodeops.vn_getattr = &devfs_getattr;
+    vnodeops.vn_read = &devfs_read;
+    vnodeops.vn_lookup = &devfs_lookup;
+    vnodeops.vn_write = &devfs_write;
+    root.v_op = &vnodeops;
+
+    vfsops.vfs_root = &devfs_root;
+    vfs->vfs_op = &vfsops;
+    vfs->vfs_data = 0;
+
+    return 0;
+}
diff --git a/devfs.h b/devfs.h
new file mode 100644
index 0000000..e7894fa
--- /dev/null
+++ b/devfs.h
@@ -0,0 +1,10 @@
+#ifndef DEVFS_H
+#define DEVFS_H
+
+#include "vfs.h"
+#include "vnode.h"
+
+int devfs_init(vfs_t *vfs);
+int devfs_add_device(char const *path, vnode_t *node);
+
+#endif /* DEVFS_H */
diff --git a/devfs.o b/devfs.o
new file mode 100644
index 0000000000000000000000000000000000000000..4b15c04dc40ff3cf36e698a9bfc0d5ccc4accab8
GIT binary patch
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diff --git a/fb.o b/fb.o
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GIT binary patch
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hbtB4X97F~EF2*$?<I#73`n1Qp2OZv_f<RN|{{U<}?;HRC

diff --git a/gdt.h b/gdt.h
index bf36d72..7641042 100644
--- a/gdt.h
+++ b/gdt.h
@@ -10,3 +10,4 @@
 void gdt_init(uint32_t tss_vaddr);
 
 #endif /* GDT_H */
+
diff --git a/gdt_asm.o b/gdt_asm.o
new file mode 100644
index 0000000000000000000000000000000000000000..98bb95331b3831e80c2880b51e584d25c0196110
GIT binary patch
literal 608
zcmb<-^>JflWMqH=Mh0dE1doBi0V-hvrZpJY7?@y6Nuoh!f-oCYmjRF?i)4ZTl+6yL
znUTZ;fa<i7_#iVtKoE$LUD5!QC;*DF05Ql85DhX@5{Qw_`v6oI4-|s|n0bmo0Zy18
zkPZME&H<!BdO>PH=7IR#E-Ebii~_It!2Glw0t|gO`Y!Yx=zG!k;4n~(L9ZmWqJ%-O
zIHS0vs3b87$g0eR&`^F+Y7RsVNHqq4xd$Y{!tn7wvI0=da03NE?tp-g|7Cy-SlBTD
z)!PC2Ah$sPBZDrC38V!;K1ok0iBBxf)hlKQc6ASS^@;a(4e|q0&cSE`F2P{6Ir)hx
h@rijU@x`en7y^1g&w%8MQ`2)(^Gb>#Zev7>7yyD{M!Wz3

literal 0
HcmV?d00001

diff --git a/gdt_asm.s b/gdt_asm.s
new file mode 100644
index 0000000..62283fc
--- /dev/null
+++ b/gdt_asm.s
@@ -0,0 +1,27 @@
+; these are functions dealing with the gdt and idt
+; see also descriptor_tables.[c,h]
+
+global gdt_load_and_set
+
+SEGSEL_KERNEL_CS equ 0x08
+SEGSEL_KERNEL_DS equ 0x10
+
+section .text
+
+; load the gdt into the cpu, and enter the kernel segments
+gdt_load_and_set:
+    mov     eax, [esp+4]        ; fetch gdt_ptr from parameter stack
+    lgdt    [eax]               ; load gdt table
+
+    ; load cs segment by doing a far jump
+    jmp     SEGSEL_KERNEL_CS:.reload_segments
+
+.reload_segments:
+    ; we only use one segment for data
+    mov     ax, SEGSEL_KERNEL_DS
+    mov     ds, ax
+    mov     ss, ax
+    mov     es, ax
+    mov     gs, ax
+    mov     fs, ax
+    ret
diff --git a/idt.c b/idt.c
index 41f464e..3808be1 100644
--- a/idt.c
+++ b/idt.c
@@ -10,8 +10,6 @@
 #define IDT_TIMER_INTERRUPT_INDEX    0x20
 #define IDT_KEYBOARD_INTERRUPT_INDEX 0x21
 
-//for part 6 of little os
-
 #define CREATE_IDT_GATE(idx) \
     create_idt_gate(idx, (uint32_t) &interrupt_handler_##idx,\
                     IDT_TRAP_GATE_TYPE, PL0);
@@ -165,3 +163,4 @@ static void create_idt_gate(uint8_t n, uint32_t handler, uint8_t type,
         (0x01 << 1)          |
         type;
 }
+
diff --git a/idt.o b/idt.o
index abf1fade31430cdf04b18f1da41897a50eb160f8..e461511aadb7fb64c6c439c95d888f14dd8f9a41 100644
GIT binary patch
literal 4188
zcmeHKL2nyH6n<-O8YgjWCp9I|l)BBfNt$Hqtv61KdT1M$6bLAwR6*k4I>`nnbsS`G
zqy_>(G7_#*P$epHfCC2*ASB>WRTUthN<tArDiQ}ca6ko#5##^}1PG9MZ|zMsGlRqr
z=#yr@_kA;dJ8$xKX0mu<=q^Q3z%>Q@u)zQpLe(DAfldfQ1C-X<Ca<Nm#!CGaQqQHd
zpyN!#v@$#m>_;C!X(i&(6!xW{`Pj0c`Ptiorm`0Wt&Tk-Xj@oO(CS%Q&;smUL2F?B
zg4W2|1+9sN1ue+_!Ufx$?^gD`poQ2Mf)-{U3R;A{DQL~?1wm_JB|+Q9W(6(A9u~CS
zY*5hlu!Nwsvt5Fwu_i&=%YMf~*t`b&*tde#!LAEhCwouOy4Y)iwx2yOXx(g4(0bSz
zLF;9sf~K<pK|8<>cr`!PbM`G%SZh^&7OTFr793`OS1J`u_d;o<Z5f57AuX~rqO~ri
zw6^k)7ATKsYFX97ms45*_2}fe=qg5lb>Zp{5z@A}+T=BL6)Ot@)gd3NtLpmr@a3ph
zy5YZiqplIdmOg#199^x$UVM3Q83qRi?u>Pw8k@`8bFn_%)Z@L$Ifoff8c98F>Sk9}
zj~$E~$#^n;m?B5%fu=n6ASep~Wk*m|%lLOaiL+>{c0t&W&Oj(O8q$u3I*)~Vj)&qW
zL$Se|^yX>^#c-ll8$HJyClyki8p~omQ5`)&H8l{5_~x;LGc3DxQ{m^zIzeaiX+)fg
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zewyPp$IBdliR15Ze1+p*aeR&Ap5q*7zS}(uOuU=pM>&3q<I@~p<oHF7zrpbjI8NuF
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zqV-F(LlW(<L^Gs`$TBfxsTi_c3|TUUEE_|Xjv>p(kR@cuGD^tinUKvhA)9AHHqV4?
zo(b7J6S8?GWb-s-D{snH-jroz$}%!#8JV(-Oj$-|KUC{GU7RnDXL32`3&_o8Cem2;
z>7qq@X%jZ3p?Zf=kaQ9c0vsXS3NTEF|F=vKh5^nJ;)i#huo>WG!WMu_gxdf<A;b&O
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z_5i$3*bDGEp$<U%l7bgnKkhfaI6xAS*6p4ej@HnsVX1~VRq)|&>3xKt7w2c}%ow6w
zsAAUj3RX_Ht+O`h6B#=L`dG0D`uOb3jFm?%KWkh1;Qgn1i*{!G4Cpl4%BCj^nHdY?
z{!hat1YD~1liWoAJkHfM>La6b8`FcM*vKwnO`OKgM)YZniY<T*m)PNMh>u(cbuu>|
zF0C`(?f$QExU|l12+3$%U)6P<6ptERyxrK;@tYf%2%6h>U(KhbC;J1(Ew}_Z<w15g
zHgCRBtoaCPlrP<h+<dX*!TTx=$I<^ouDS0e^t=XaygEhjhxEPCdng{oC*K?IX%uvi
H;KutG*5LAB

literal 3624
zcma)8Z)hAv6#wnrrMaY+<dVkP+D5N`lQhltwzo-JsSsPwR%l8p9##~tm*ip+lS{qZ
zpwZe^qHrNpA}IL5FM<UH5fLmZDi#|{MN!cYei3SEagcnlAwq;md~feIxtkfm2fM%d
z{od@G_hx5j_FVkfgN9+iGXs9CGT>;a;IUn3K?qeyOx>EC+c0o7KEGV~G3!(D1s8`g
zZ1fC62p=$cC0wEz;%7zki7yq+FWytMfOtdED#S~Qwnm&*v`X=Wq6NiKMXM6FqE(BC
zqOBDnMGJ{Vnz8bFYs5`Os}(;eTAlbz(Zb>#MXMLDDO!U#uW0MUh@wTrNk!Wt9#FKc
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zM%m3unNi3U3*h$h3ZX{%&cd7rTs1!es3gjH@L0aGorwGMysetw?On<%a3|3SOF^I>
z^UIsKO~x@BDBku0b?;%i@0a*7iJy|VBk{b%-<0?V62BtxUnD*!@sh0>obURQ31;3V
z@h*ucBt9(ha}wum#xsupuEf8P_)iiS68}fy4ZPfo#_^jaeo*2kBt9VV=OsQP@rx4w
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z{*iPx8P#Z(M%$~=Vj9iXXdN1@Q={$EX!|wV0gYy93(-|#=}NJ5wOG1hEL}C0t{h8O
zkEJWf(p41G<r&lE8Pnw%)8!e{<r&lE8Pnw%)8%RFX5QA#ysfLq)>UNdDzbGI*}97C
zeJHH&WNsqYml_#yzkrdkRDY6|eKMEky|jidqYB{j)mRI(GKPTr7|D5pu@*=()&UcY
z^x<7#tOwp=YyduDTnAiZq{Hr4MhbeHaXnB$`;bA0!$!spKs)0`I?fpH0(hS^=&%@K
zq(koo#wOrZ#=C)wjQ0SaFh+py7`FhwF>VF^V%!E)(SBjjA=AXT1F#r(0&&J>;4#J)
zV3d)HeUWh&@H%4~?YE5d5Ar!<JMbf;3EX1bLuVlEH@+wkCFFTKRK(*&e7uOy6p>Pe
zkDl!+BFx;xsFUg?bg~5;^jg{Ui0P!Cbzt_VoD|I7Tn=X6*yw0FLt19cNt;KGC)#sP
zs_!Y7+&ev(9LT0d`Q`jiqba0Q7%L~aP3^Okt7q(E<8zzJbMt0?z8W}1P6GFN{_~(C
z9yG-+_d<N=HArXk;?dN){XO@8^`ohEpJ8O<ejSCTd*^t3(J$3XY<B$a1!h9#joV#p
z(<^XIP`{JKHUrne_7GjA^<JlMftI;jFaHyH_0p0r`)m4>`aMdTXWqDs-k9v`q5xqU
Xo4UK>a6FFBW0t1gLxY(mf*0>!%;%>w

diff --git a/interrupt.c b/interrupt.c
index af517eb..c02215a 100644
--- a/interrupt.c
+++ b/interrupt.c
@@ -8,10 +8,8 @@
 #include "log.h"
 #include "constants.h"
 
-//interupt handler for part 6
-
 static interrupt_handler_t interrupt_handlers[IDT_NUM_ENTRIES];
-/*
+
 uint32_t register_interrupt_handler(uint32_t interrupt,
                                     interrupt_handler_t handler)
 {
@@ -28,7 +26,7 @@ uint32_t register_interrupt_handler(uint32_t interrupt,
     interrupt_handlers[interrupt] = handler;
     return 0;
 }
-*/
+
 void interrupt_handler(cpu_state_t state, idt_info_t info, stack_state_t exec)
 {
     if (interrupt_handlers[info.idt_index] != NULL) {
diff --git a/interrupt.o b/interrupt.o
index 42b903ae30c1e725c91089ceb793fe8611567535..4e6d6be38d1130adff0f1542cb7234d55d4e180a 100644
GIT binary patch
delta 376
zcmeyt^@n?c0^^s7io(8)H7YFs85kJK*mp1jsn^yZfptJuDO5nK+eL+?o23;f#L#-6
z1S%>577bD1=oA6V>;Oq0o@g?E;)5Bo0zkG5NB{_YArwOfkTwAEH#ahJGfIMlg%}ta
zG(kc@JQ>Qjo;;OFKeZ?|J+rtZwJ1I_4@ef37L>$iB<7{$q!uyc<fj8g)AGSO8Ce(@
zoPjz)bOe-6htelOG#dlMIVgP@NHg&;Ferd%CI$wR$(+oK86Qku%dE`m!_2^7G5IR9
zGLs17<X_BcObU#Xl~}-(7mFHW#^gd4b;h}qXR@fXE&ztojLAn?lv!JVngk}lWl?6F
fGFgySoz((p=!MC)tjZD`Kp7XHH821QSP%dJ|L{qS

delta 209
zcmeyv{ex?Q0%O5MMd68!^C$DN@J?1>oWYsFz`!5_#0;CSGIBF=P6o1s7#JChCjVs8
zpKQo1t;N6%6k=pyV32~+H6WUefuRvfw*hG;pdy9Iz08XlCr>tHQD%L>#K532Ig&-0
z={UpWIu<pi2Mm*!L8x;qYK$6_zp|(^#!i-HRcB3LWMF8Se33<Xatx~gD+e<J1IOe-
hR%KQJAS)hdnDFE^K=CI)RR<;?1d1;K8f^^{2LLHXD#QQ)


From 65bf6977da1d2072591210d94061bb8101d14737 Mon Sep 17 00:00:00 2001
From: Sean Lachhander <slachhander@albany.edu>
Date: Wed, 26 Apr 2017 23:45:17 -0400
Subject: [PATCH 2/2] Update README.md

---
 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 33f75d8..3affa44 100755
--- a/README.md
+++ b/README.md
@@ -1 +1,3 @@
-# LittleOS
\ No newline at end of file
+# LittleOS
+
+This project consists of writing an Operating System in x86 architecture. This project requires work within a UNIX/Linux environment, systems programming, C language, and computer systems in general.