armthumb.c
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///////////////////////////////////////////////////////////////////////////////
//
/// \file armthumb.c
/// \brief Filter for ARM-Thumb binaries
///
// Authors: Igor Pavlov
// Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "simple_private.h"
static size_t
armthumb_code(lzma_simple *simple lzma_attribute((unused)),
uint32_t now_pos, bool is_encoder,
uint8_t *buffer, size_t size)
{
size_t i;
for (i = 0; i + 4 <= size; i += 2) {
if ((buffer[i + 1] & 0xF8) == 0xF0
&& (buffer[i + 3] & 0xF8) == 0xF8) {
uint32_t src = ((buffer[i + 1] & 0x7) << 19)
| (buffer[i + 0] << 11)
| ((buffer[i + 3] & 0x7) << 8)
| (buffer[i + 2]);
src <<= 1;
uint32_t dest;
if (is_encoder)
dest = now_pos + (uint32_t)(i) + 4 + src;
else
dest = src - (now_pos + (uint32_t)(i) + 4);
dest >>= 1;
buffer[i + 1] = 0xF0 | ((dest >> 19) & 0x7);
buffer[i + 0] = (dest >> 11);
buffer[i + 3] = 0xF8 | ((dest >> 8) & 0x7);
buffer[i + 2] = (dest);
i += 2;
}
}
return i;
}
static lzma_ret
armthumb_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
const lzma_filter_info *filters, bool is_encoder)
{
return lzma_simple_coder_init(next, allocator, filters,
&armthumb_code, 0, 4, 2, is_encoder);
}
extern lzma_ret
lzma_simple_armthumb_encoder_init(lzma_next_coder *next,
lzma_allocator *allocator, const lzma_filter_info *filters)
{
return armthumb_coder_init(next, allocator, filters, true);
}
extern lzma_ret
lzma_simple_armthumb_decoder_init(lzma_next_coder *next,
lzma_allocator *allocator, const lzma_filter_info *filters)
{
return armthumb_coder_init(next, allocator, filters, false);
}