From 7c1d3869d8cf4341acedbe7c662e8ac1ca935666 Mon Sep 17 00:00:00 2001
From: Egor Ananyin <ananinegor@gmail.com>
Date: Fri, 22 May 2020 19:46:43 +0300
Subject: Decompile libmath

---
 arm9/lib/src/MATH_crc.c | 150 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 arm9/lib/src/MATH_crc.c

(limited to 'arm9/lib/src/MATH_crc.c')

diff --git a/arm9/lib/src/MATH_crc.c b/arm9/lib/src/MATH_crc.c
new file mode 100644
index 00000000..ec0ccad0
--- /dev/null
+++ b/arm9/lib/src/MATH_crc.c
@@ -0,0 +1,150 @@
+#include "global.h"
+#include "MATH_crc.h"
+
+ARM_FUNC void MATHi_CRC8InitTable(struct MATHCRC8Table *table, u8 poly) {
+    u32 r, i, j;
+    u8 *t = table->table;
+
+    for (i = 0; i < 256; i++) {
+        r = i;
+        for (j = 0; j < 8; j++) {
+            if (r & 0x80) {
+                r = (r << 1) ^ poly;
+            }
+            else {
+                r <<= 1;
+            }
+        }
+        t[i] = r;
+    }
+}
+
+ARM_FUNC void MATHi_CRC8Update(const struct MATHCRC8Table *table, MATHCRC8Context *context, const void *input, u32 length) {
+    u32 r, i;
+    const u8* t = table->table;
+    u8* data = (u8*)input;
+
+    r = *context;
+    for (i = 0; i < length; i++) {
+        r = t[(r ^ *data) & 0xff];
+        data++;
+    }
+    *context = r;
+}
+
+ARM_FUNC void MATHi_CRC16InitTable(struct MATHCRC16Table *table, u16 poly) {
+    u32 r, i, j;
+    u16 *t = table->table;
+
+    for (i = 0; i < 256; i++) {
+        r = i << 8;
+        for (j = 0; j < 8; j++) {
+            if (r & 0x8000) {
+                r = (r << 1) ^ poly;
+            }
+            else {
+                r <<= 1;
+            }
+        }
+        t[i] = r;
+    }
+}
+
+ARM_FUNC void MATHi_CRC16InitTableRev(struct MATHCRC16Table *table, u16 poly) {
+    u32 r, i, j;
+    u16 *t = table->table;
+
+    for (i = 0; i < 256; i++) {
+        r = i;
+        for (j = 0; j < 8; j++) {
+            if (r & 1) {
+                r = (r >> 1) ^ poly;
+            }
+            else {
+                r >>= 1;
+            }
+        }
+        t[i] = r;
+    }
+}
+
+ARM_FUNC void MATHi_CRC16Update(const struct MATHCRC16Table *table, MATHCRC16Context *context, const void *input, u32 length) {
+    u32 r, i;
+    const u16* t = table->table;
+    u8* data = (u8*)input;
+
+    r = *context;
+    for (i = 0; i < length; i++) {
+        r = (r << 8) ^ t[((r >> 8) ^ *data) & 0xff];
+        data++;
+    }
+    *context = r;
+}
+
+ARM_FUNC void MATHi_CRC16UpdateRev(const struct MATHCRC16Table *table, MATHCRC16Context *context, const void *input, u32 length) {
+    u32 r, i;
+    const u16* t = table->table;
+    u8* data = (u8*)input;
+
+    r = *context;
+    for (i = 0; i < length; i++) {
+        r = (r >> 8) ^ t[(r ^ *data) & 0xff];
+        data++;
+    }
+    *context = r;
+}
+
+ARM_FUNC void MATHi_CRC32InitTableRev(struct MATHCRC32Table *table, u32 poly) {
+    u32 r, i, j;
+    u32 *t = table->table;
+
+    for (i = 0; i < 256; i++) {
+        r = i;
+        for (j = 0; j < 8; j++) {
+            if (r & 1) {
+                r = (r >> 1) ^ poly;
+            }
+            else {
+                r >>= 1;
+            }
+        }
+        t[i] = r;
+    }
+}
+
+ARM_FUNC void MATHi_CRC32UpdateRev(const struct MATHCRC32Table *table, MATHCRC32Context *context, const void *input, u32 length) {
+    u32 r, i;
+    const u32* t = table->table;
+    u8* data = (u8*)input;
+
+    r = *context;
+    for (i = 0; i < length; i++) {
+        r = (r >> 8) ^ t[(r ^ *data) & 0xff];
+        data++;
+    }
+    *context = r;
+}
+
+ARM_FUNC u8 MATH_CalcCRC8(const struct MATHCRC8Table *table, const void *data, u32 dataLength) {
+    MATHCRC8Context ctx = 0;
+    MATHi_CRC8Update(table, &ctx, data, dataLength);
+    return ctx;
+}
+
+ARM_FUNC u16 MATH_CalcCRC16(const struct MATHCRC16Table *table, const void *data, u32 dataLength) {
+    MATHCRC16Context ctx = 0;
+    MATHi_CRC16UpdateRev(table, &ctx, data, dataLength);
+    return ctx;
+}
+
+ARM_FUNC u16 MATH_CalcCRC16CCITT(const struct MATHCRC16Table *table, const void *data, u32 dataLength) {
+    MATHCRC16Context ctx = 0xffff;
+    MATHi_CRC16Update(table, &ctx, data, dataLength);
+    return ctx;
+}
+
+ARM_FUNC u32 MATH_CalcCRC32(const struct MATHCRC32Table *table, const void *data, u32 dataLength) {
+    MATHCRC32Context ctx = ~0;
+    MATHi_CRC32UpdateRev(table, &ctx, data, dataLength);
+    return ~ctx;
+}
-- 
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