44 lines
991 B
C
44 lines
991 B
C
|
/*
|
||
|
|
* Bitstream encoder.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "duk_internal.h"
|
||
|
|
|
||
|
|
DUK_INTERNAL void duk_be_encode(duk_bitencoder_ctx *ctx, duk_uint32_t data, duk_small_int_t bits) {
|
||
|
|
duk_uint8_t tmp;
|
||
|
|
|
||
|
|
DUK_ASSERT(ctx != NULL);
|
||
|
|
DUK_ASSERT(ctx->currbits < 8);
|
||
|
|
|
||
|
|
/* This limitation would be fixable but adds unnecessary complexity. */
|
||
|
|
DUK_ASSERT(bits >= 1 && bits <= 24);
|
||
|
|
|
||
|
|
ctx->currval = (ctx->currval << bits) | data;
|
||
|
|
ctx->currbits += bits;
|
||
|
|
|
||
|
|
while (ctx->currbits >= 8) {
|
||
|
|
if (ctx->offset < ctx->length) {
|
||
|
|
tmp = (duk_uint8_t) ((ctx->currval >> (ctx->currbits - 8)) & 0xff);
|
||
|
|
ctx->data[ctx->offset++] = tmp;
|
||
|
|
} else {
|
||
|
|
/* If buffer has been exhausted, truncate bitstream */
|
||
|
|
ctx->truncated = 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
ctx->currbits -= 8;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
DUK_INTERNAL void duk_be_finish(duk_bitencoder_ctx *ctx) {
|
||
|
|
duk_small_int_t npad;
|
||
|
|
|
||
|
|
DUK_ASSERT(ctx != NULL);
|
||
|
|
DUK_ASSERT(ctx->currbits < 8);
|
||
|
|
|
||
|
|
npad = (duk_small_int_t) (8 - ctx->currbits);
|
||
|
|
if (npad > 0) {
|
||
|
|
duk_be_encode(ctx, 0, npad);
|
||
|
|
}
|
||
|
|
DUK_ASSERT(ctx->currbits == 0);
|
||
|
|
}
|