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/* Entry point for the rot13 example.
*
* This example shows how you can fulfill wasm module imports in your C
* program, and access linear memory.
*
* The program reads arguments from the command line, and [rot13] encodes them,
* e.g.:
*
* ```
* $ rot13 foo bar
* foo -> sbb
* bar -> one
* ```
*
* [rot13]: https://en.wikipedia.org/wiki/ROT13
*/
#include <stdio.h>
#include <stdlib.h>
/* Uncomment this to define rot13_init rot13_Z_rot13Z_vv instead. */
/* #define WASM_RT_MODULE_PREFIX rot13_ */
#include "rot13.h"
/* Define the imports as declared in rot13.h. */
wasm_rt_memory_t (*Z_hostZ_mem);
u32 (*Z_hostZ_fill_bufZ_iii)(u32, u32);
void (*Z_hostZ_buf_doneZ_vii)(u32, u32);
/* Define the implementations of the imports. */
static wasm_rt_memory_t s_memory;
static u32 fill_buf(u32 ptr, u32 size);
static void buf_done(u32 ptr, u32 size);
/* The string that is currently being processed. This needs to be static
* because the buffer is filled in the callback. */
static const char* s_input;
int main(int argc, char** argv) {
/* Initialize the rot13 module. Since we didn't define WASM_RT_MODULE_PREFIX,
the initialization function is called `init`. */
init();
/* Allocate 1 page of wasm memory (64KiB). */
wasm_rt_allocate_memory(&s_memory, 1, 1);
/* Provide the imports expected by the module: "host.mem", "host.fill_buf"
* and "host.buf_done". Their mangled names are `Z_hostZ_mem`,
* `Z_hostZ_fill_bufZ_iii` and `Z_hostZ_buf_doneZ_vii`. */
Z_hostZ_mem = &s_memory;
Z_hostZ_fill_bufZ_iii = &fill_buf;
Z_hostZ_buf_doneZ_vii = &buf_done;
/* Call `rot13` on each argument, using the mangled name. */
while (argc > 1) {
/* Move to next arg. Do this first, so the program name is skipped. */
argc--; argv++;
s_input = argv[0];
Z_rot13Z_vv();
}
return 0;
}
/* Fill the wasm buffer with the input to be rot13'd.
*
* params:
* ptr: The wasm memory address of the buffer to fill data.
* size: The size of the buffer in wasm memory.
* result:
* The number of bytes filled into the buffer. (Must be <= size).
*/
u32 fill_buf(u32 ptr, u32 size) {
for (size_t i = 0; i < size; ++i) {
if (s_input[i] == 0) {
return i;
}
s_memory.data[ptr + i] = s_input[i];
}
return size;
}
/* Called when the wasm buffer has been rot13'd.
*
* params:
* ptr: The wasm memory address of the buffer.
* size: The size of the buffer in wasm memory.
*/
void buf_done(u32 ptr, u32 size) {
/* The output buffer is not necessarily null-terminated, so use the %*.s
* printf format to limit the number of characters printed. */
printf("%s -> %.*s\n", s_input, (int)size, &s_memory.data[ptr]);
}
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