From 1780fc54b9236bf04603b6b04920166f289d6a1c Mon Sep 17 00:00:00 2001
From: qydysky <qydysky@foxmail.com>
Date: Sun, 4 Aug 2024 09:28:55 +0800
Subject: [PATCH] 1

---
 decoder/tool/B_I.go | 134 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 decoder/tool/B_I.go

diff --git a/decoder/tool/B_I.go b/decoder/tool/B_I.go
new file mode 100644
index 0000000..a8d1498
--- /dev/null
+++ b/decoder/tool/B_I.go
@@ -0,0 +1,134 @@
+package mp4
+
+/*
+整数 字节转换区
+64 8字节
+32 4字节
+16 2字节
+*/
+func Itob64(v int64) []byte {
+	//binary.BigEndian.PutUint64
+	b := make([]byte, 8)
+	b[0] = byte(v >> 56)
+	b[1] = byte(v >> 48)
+	b[2] = byte(v >> 40)
+	b[3] = byte(v >> 32)
+	b[4] = byte(v >> 24)
+	b[5] = byte(v >> 16)
+	b[6] = byte(v >> 8)
+	b[7] = byte(v)
+	return b
+}
+
+func Itob32(v int32) []byte {
+	//binary.BigEndian.PutUint32
+	b := make([]byte, 4)
+	b[0] = byte(v >> 24)
+	b[1] = byte(v >> 16)
+	b[2] = byte(v >> 8)
+	b[3] = byte(v)
+	return b
+}
+
+func Itob16(v int16) []byte {
+	//binary.BigEndian.PutUint16
+	b := make([]byte, 2)
+	b[0] = byte(v >> 8)
+	b[1] = byte(v)
+	return b
+}
+
+func Btoi(b []byte, offset int, size int) int64 {
+	if size > 8 {
+		panic("最大8位")
+	}
+
+	bu := make([]byte, 8)
+	l := len(b) - offset
+	if l > size {
+		l = size
+	}
+	for i := 0; i < size && i < l; i++ {
+		bu[i+8-size] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint64
+	return int64(uint64(bu[7]) | uint64(bu[6])<<8 | uint64(bu[5])<<16 | uint64(bu[4])<<24 |
+		uint64(bu[3])<<32 | uint64(bu[2])<<40 | uint64(bu[1])<<48 | uint64(bu[0])<<56)
+}
+
+func Btoui32(b []byte, offset int) uint32 {
+	s := 4
+	bu := make([]byte, s)
+	l := len(b) - offset
+	if l > s {
+		l = s
+	}
+	for i := 0; i < s && i < l; i++ {
+		bu[i+s-l] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint32
+	return uint32(bu[3]) | uint32(bu[2])<<8 | uint32(bu[1])<<16 | uint32(bu[0])<<24
+}
+
+func Btoi32(b []byte, offset int) int32 {
+	s := 4
+	bu := make([]byte, s)
+	l := len(b) - offset
+	if l > s {
+		l = s
+	}
+	for i := 0; i < s && i < l; i++ {
+		bu[i+s-l] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint32
+	return int32((uint32(bu[3]) | uint32(bu[2])<<8 | uint32(bu[1])<<16 | uint32(bu[0])<<24))
+}
+
+func Btoui16(b []byte, offset int) uint16 {
+	s := 2
+	bu := make([]byte, s)
+	l := len(b) - offset
+	if l > s {
+		l = s
+	}
+	for i := 0; i < s && i < l; i++ {
+		bu[i+s-l] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint16
+	return uint16(bu[1]) | uint16(bu[0])<<8
+}
+
+func Btoi16(b []byte, offset int) int16 {
+	s := 2
+	bu := make([]byte, s)
+	l := len(b) - offset
+	if l > s {
+		l = s
+	}
+	for i := 0; i < s && i < l; i++ {
+		bu[i+s-l] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint16
+	return int16(uint16(bu[1]) | uint16(bu[0])<<8)
+}
+
+func Btoi64(b []byte, offset int) int64 {
+	s := 8
+	bu := make([]byte, s)
+	l := len(b) - offset
+	if l > s {
+		l = s
+	}
+	for i := 0; i < s && i < l; i++ {
+		bu[i+s-l] = b[offset+i]
+	}
+
+	//binary.BigEndian.Uint64
+	return int64(uint64(bu[7]) | uint64(bu[6])<<8 | uint64(bu[5])<<16 | uint64(bu[4])<<24 |
+		uint64(bu[3])<<32 | uint64(bu[2])<<40 | uint64(bu[1])<<48 | uint64(bu[0])<<56)
+}
-- 
2.39.2