From 971b2f4803da963993afc0d5aa640fc4d93fcbda Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Mon, 28 Nov 2022 15:00:34 +0400
Subject: [PATCH] Add i386 stuff (#116)

* Add struct KernAux_Arch_I386_IDTE
* Add struct KernAux_Arch_I386_DTR
* Remove unnecessary static check
* Add func KernAux_Arch_I386_IDTE_set_offset
---
 .gitignore                  |  1 +
 include/kernaux/arch/i386.h | 27 +++++++++++++++++++++++++++
 src/arch/i386.c             | 11 ++++++++---
 tests/Makefile.am           | 12 ++++++++++++
 tests/test_arch_i386.c      | 33 +++++++++++++++++++++++++++++++++
 5 files changed, 81 insertions(+), 3 deletions(-)
 create mode 100644 tests/test_arch_i386.c

diff --git a/.gitignore b/.gitignore
index a7343fb..0637360 100644
--- a/.gitignore
+++ b/.gitignore
@@ -126,6 +126,7 @@
 /tests/multiboot2_header_print2
 /tests/multiboot2_info_print1
 /tests/multiboot2_info_print2
+/tests/test_arch_i386
 /tests/test_cmdline
 /tests/test_cmdline_gen
 /tests/test_cmdline_gen.c
diff --git a/include/kernaux/arch/i386.h b/include/kernaux/arch/i386.h
index 1622004..1d364ab 100644
--- a/include/kernaux/arch/i386.h
+++ b/include/kernaux/arch/i386.h
@@ -53,6 +53,16 @@ extern "C" {
 
 #include <kernaux/macro/packing_start.run>
 
+// Global, local or interrupt descriptor table register
+// TODO: validate this according to spec
+struct KernAux_Arch_I386_DTR {
+    uint16_t size;
+    uint32_t offset;
+}
+KERNAUX_PACKING_ATTR;
+
+KERNAUX_STATIC_TEST_STRUCT_SIZE(KernAux_Arch_I386_DTR, 6);
+
 // Global or local descriptor table entry
 // TODO: validate this according to spec
 struct KernAux_Arch_I386_DTE {
@@ -74,8 +84,25 @@ struct KernAux_Arch_I386_DTE {
 }
 KERNAUX_PACKING_ATTR;
 
+// Interrupt descriptor table entry
+// TODO: validate this according to spec
+typedef struct KernAux_Arch_I386_IDTE {
+    uint16_t offset_low;
+    uint16_t selector;
+    uint8_t  _zero0;
+    uint8_t  flags;
+    uint16_t offset_high;
+}
+KERNAUX_PACKING_ATTR
+*KernAux_Arch_I386_IDTE;
+
 KERNAUX_STATIC_TEST_STRUCT_SIZE(KernAux_Arch_I386_DTE, 8);
 
+void KernAux_Arch_I386_IDTE_set_offset(
+    KernAux_Arch_I386_IDTE idte,
+    uint32_t address
+);
+
 /**
  * @brief Task state segment
  * @see The manual, page 132, figure 7-1
diff --git a/src/arch/i386.c b/src/arch/i386.c
index edb517a..7337f74 100644
--- a/src/arch/i386.c
+++ b/src/arch/i386.c
@@ -4,6 +4,11 @@
 
 #include <kernaux/arch/i386.h>
 
-__attribute__((unused))
-static const int
-TSS_validation[sizeof(struct KernAux_Arch_I386_TSS) == 104 ? 1 : -1];
+void KernAux_Arch_I386_IDTE_set_offset(
+    const KernAux_Arch_I386_IDTE idte,
+    const uint32_t address
+)
+{
+    idte->offset_low  = 0xFFFF & address;
+    idte->offset_high = 0xFFFF & (address >> 16);
+}
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8049c44..6c15a82 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -56,6 +56,18 @@ multiboot2_info_print2_SOURCES = \
 	multiboot2_info_example2.h
 endif
 
+##################
+# test_arch_i386 #
+##################
+
+if WITH_ARCH_I386
+TESTS += test_arch_i386
+test_arch_i386_LDADD = $(top_builddir)/libkernaux.la
+test_arch_i386_SOURCES = \
+	main.c \
+	test_arch_i386.c
+endif
+
 ################
 # test_cmdline #
 ################
diff --git a/tests/test_arch_i386.c b/tests/test_arch_i386.c
new file mode 100644
index 0000000..37a931a
--- /dev/null
+++ b/tests/test_arch_i386.c
@@ -0,0 +1,33 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <kernaux/arch/i386.h>
+
+#include <assert.h>
+#include <string.h>
+
+static void test_idte_set_offset();
+
+void test_main()
+{
+    test_idte_set_offset();
+}
+
+void test_idte_set_offset()
+{
+    struct KernAux_Arch_I386_IDTE idte;
+    memset(&idte, 0, sizeof(idte));
+
+    KernAux_Arch_I386_IDTE_set_offset(&idte, 0);
+    assert(idte.offset_high == 0);
+    assert(idte.offset_low  == 0);
+
+    KernAux_Arch_I386_IDTE_set_offset(&idte, 0xFFFFFFFF);
+    assert(idte.offset_high == 0xFFFF);
+    assert(idte.offset_low  == 0xFFFF);
+
+    KernAux_Arch_I386_IDTE_set_offset(&idte, 0x12345678);
+    assert(idte.offset_high == 0x1234);
+    assert(idte.offset_low  == 0x5678);
+}