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#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
uint64_t read_leb128_u(int _fd, int max_size) {
uint8_t read_bytes = 0U;
uint8_t byte = 0;
uint64_t result = 0U;
uint32_t shift = 0U;
do {
read(_fd, &byte, 1);read_bytes++;read_bytes++;
result |= (byte & 0x7f) << shift;
shift += 7;
} while(((byte & 0x80) != 0) && (read_bytes < max_size));
return result;
}
int64_t read_leb128_s(int _fd, int max_size) {
uint8_t byte;
uint8_t read_bytes = 0U;
uint8_t last_byte;
int64_t result = 0;
uint32_t shift = 0U;
read(_fd, &byte, 1);
do {
read(_fd, &byte, 1);read_bytes++;
result |= (byte & 0x7f) << shift;
last_byte = byte;
shift += 7;
} while(((byte & 0x80) != 0) && read_bytes < max_size);
if ((last_byte & 0x40) != 0) result |= -(1 << shift);
return result;
}
#define READ_VAR_UINT_1(FD) read_leb128_u(FD, 1)
#define READ_VAR_UINT_7(FD) read_leb128_u(FD, 1)
#define READ_VAR_UINT_32(FD) read_leb128_u(FD, 5)
#define READ_VAR_INT_1(FD) read_leb128_s(FD, 1)
#define READ_VAR_INT_7(FD) read_leb128_s(FD, 1)
#define READ_VAR_INT_32(FD) read_leb128_s(FD, 5)
#pragma weak main
int main (int argc, char** argv) {
int wasm = open("./test.wasm", O_RDONLY);
uint64_t test_u = 0U;
int64_t test_s = 0;
unsigned char test_byte;
unsigned char byte;
uint32_t word;
uint32_t counter = 0U;
read(wasm, &word, 8);
printf("test_byte:%08x\n", word);
lseek(wasm, 9, SEEK_SET);
read(wasm, &word, 8);
printf("test_byte:%08x\n", word);
lseek(wasm, 9, SEEK_SET);
test_u = READ_VAR_UINT_32(wasm);
printf("read u res is: %lu.\n", test_u);
lseek(wasm, 0, SEEK_SET);
while(read(wasm, &word, sizeof(uint32_t))) {
//printf("%d:%02x\t", counter, word);
counter++;
}
printf("\n");
return 0;
}
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