/* inffast.c -- fast decoding
 * Copyright (C) 1995-2004 Mark Adler
* SPDX-License-Identifier:	GPL-2.0+
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* U-Boot: we already included these
#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"
*/

#ifndef ASMINF

/* Allow machine dependent optimization for post-increment or pre-increment.
   Based on testing to date,
   Pre-increment preferred for:
   - PowerPC G3 (Adler)
   - MIPS R5000 (Randers-Pehrson)
   Post-increment preferred for:
   - none
   No measurable difference:
   - Pentium III (Anderson)
   - M68060 (Nikl)
 */
#ifdef POSTINC
#define OFF 0
#define PUP(a) *(a)++
#else
#define OFF 1
#define PUP(a) *++(a)
#endif

/*
   Decode literal, length, and distance codes and write out the resulting
   literal and match bytes until either not enough input or output is
   available, an end-of-block is encountered, or a data error is encountered.
   When large enough input and output buffers are supplied to inflate(), for
   example, a 16K input buffer and a 64K output buffer, more than 95% of the
   inflate execution time is spent in this routine.

   Entry assumptions:

			state->mode == LEN
			strm->avail_in >= 6
			strm->avail_out >= 258
			start >= strm->avail_out
			state->bits < 8

   On return, state->mode is one of:

			LEN -- ran out of enough output space or enough available input
			TYPE -- reached end of block code, inflate() to interpret next block
			BAD -- error in block data

   Notes:

    - The maximum input bits used by a length/distance pair is 15 bits for the
      length code, 5 bits for the length extra, 15 bits for the distance code,
      and 13 bits for the distance extra.  This totals 48 bits, or six bytes.
      Therefore if strm->avail_in >= 6, then there is enough input to avoid
      checking for available input while decoding.

    - The maximum bytes that a single length/distance pair can output is 258
      bytes, which is the maximum length that can be coded.  inflate_fast()
      requires strm->avail_out >= 258 for each loop to avoid checking for
      output space.
 */
void inflate_fast(z_streamp strm, unsigned start)
/* start: inflate()'s starting value for strm->avail_out */
{
	struct inflate_state FAR *state;
	unsigned char FAR *in; /* local strm->next_in */
	unsigned char FAR *last; /* while in < last, enough input available */
	unsigned char FAR *out; /* local strm->next_out */
	unsigned char FAR *beg; /* inflate()'s initial strm->next_out */
	unsigned char FAR *end; /* while out < end, enough space available */
#ifdef INFLATE_STRICT
	unsigned dmax; /* maximum distance from zlib header */
#endif
	unsigned wsize; /* window size or zero if not using window */
	unsigned whave; /* valid bytes in the window */
	unsigned write; /* window write index */
	unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */
	unsigned long hold; /* local strm->hold */
	unsigned bits; /* local strm->bits */
	code const FAR *lcode; /* local strm->lencode */
	code const FAR *dcode; /* local strm->distcode */
	unsigned lmask; /* mask for first level of length codes */
	unsigned dmask; /* mask for first level of distance codes */
	code this; /* retrieved table entry */
	unsigned op; /* code bits, operation, extra bits, or */
	/*  window position, window bytes to copy */
	unsigned len; /* match length, unused bytes */
	unsigned dist; /* match distance */
	unsigned char FAR *from; /* where to copy match from */

	/* copy state to local variables */
	state = (struct inflate_state FAR *)strm->state;
	in    = strm->next_in - OFF;
	last  = in + (strm->avail_in - 5);
	if (in > last && strm->avail_in > 5) {
		/*
			* overflow detected, limit strm->avail_in to the
			* max. possible size and recalculate last
			*/
		strm->avail_in = 0xffffffff - (uintptr_t)in;
		last	   = in + (strm->avail_in - 5);
	}
	out = strm->next_out - OFF;
	beg = out - (start - strm->avail_out);
	end = out + (strm->avail_out - 257);
#ifdef INFLATE_STRICT
	dmax = state->dmax;
#endif
	wsize  = state->wsize;
	whave  = state->whave;
	write  = state->write;
	window = state->window;
	hold   = state->hold;
	bits   = state->bits;
	lcode  = state->lencode;
	dcode  = state->distcode;
	lmask  = (1U << state->lenbits) - 1;
	dmask  = (1U << state->distbits) - 1;

	/* decode literals and length/distances until end-of-block or not enough
       input data or output space */
	do {
		if (bits < 15) {
			hold += (unsigned long)(PUP(in)) << bits;
			bits += 8;
			hold += (unsigned long)(PUP(in)) << bits;
			bits += 8;
		}
		this = lcode[hold & lmask];
	dolen:
		op = (unsigned)(this.bits);
		hold >>= op;
		bits -= op;
		op = (unsigned)(this.op);
		if (op == 0) { /* literal */
			Tracevv((stderr,
				 this.val >= 0x20 && this.val < 0x7f ?
					 "inflate:         literal '%c'\n" :
					 "inflate:         literal 0x%02x\n",
				 this.val));
			PUP(out) = (unsigned char)(this.val);
		} else if (op & 16) { /* length base */
			len = (unsigned)(this.val);
			op &= 15; /* number of extra bits */
			if (op) {
				if (bits < op) {
					hold += (unsigned long)(PUP(in))
						<< bits;
					bits += 8;
				}
				len += (unsigned)hold & ((1U << op) - 1);
				hold >>= op;
				bits -= op;
			}
			Tracevv((stderr, "inflate:         length %u\n", len));
			if (bits < 15) {
				hold += (unsigned long)(PUP(in)) << bits;
				bits += 8;
				hold += (unsigned long)(PUP(in)) << bits;
				bits += 8;
			}
			this = dcode[hold & dmask];
		dodist:
			op = (unsigned)(this.bits);
			hold >>= op;
			bits -= op;
			op = (unsigned)(this.op);
			if (op & 16) { /* distance base */
				dist = (unsigned)(this.val);
				op &= 15; /* number of extra bits */
				if (bits < op) {
					hold += (unsigned long)(PUP(in))
						<< bits;
					bits += 8;
					if (bits < op) {
						hold += (unsigned long)(PUP(in))
							<< bits;
						bits += 8;
					}
				}
				dist += (unsigned)hold & ((1U << op) - 1);
#ifdef INFLATE_STRICT
				if (dist > dmax) {
					strm->msg =
						(char *)"invalid distance too far back";
					state->mode = BAD;
					break;
				}
#endif
				hold >>= op;
				bits -= op;
				Tracevv((stderr,
					 "inflate:         distance %u\n",
					 dist));
				op = (unsigned)(out -
						beg); /* max distance in output */
				if (dist > op) { /* see if copy from window */
					op = dist -
					     op; /* distance back in window */
					if (op > whave) {
						strm->msg =
							(char *)"invalid distance too far back";
						state->mode = BAD;
						break;
					}
					from = window - OFF;
					if (write == 0) { /* very common case */
						from += wsize - op;
						if (op <
						    len) { /* some from window */
							len -= op;
							do {
								PUP(out) = PUP(
									from);
							} while (--op);
							from = out -
							       dist; /* rest from output */
						}
					} else if (write <
						   op) { /* wrap around window */
						from += wsize + write - op;
						op -= write;
						if (op <
						    len) { /* some from end of window */
							len -= op;
							do {
								PUP(out) = PUP(
									from);
							} while (--op);
							from = window - OFF;
							if (write <
							    len) { /* some from start of window */
								op = write;
								len -= op;
								do {
									PUP(out) = PUP(
										from);
								} while (--op);
								from = out -
								       dist; /* rest from output */
							}
						}
					} else { /* contiguous in window */
						from += write - op;
						if (op <
						    len) { /* some from window */
							len -= op;
							do {
								PUP(out) = PUP(
									from);
							} while (--op);
							from = out -
							       dist; /* rest from output */
						}
					}
					while (len > 2) {
						PUP(out) = PUP(from);
						PUP(out) = PUP(from);
						PUP(out) = PUP(from);
						len -= 3;
					}
					if (len) {
						PUP(out) = PUP(from);
						if (len > 1)
							PUP(out) = PUP(from);
					}
				} else {
					unsigned short *sout;
					unsigned long loops;

					from = out -
					       dist; /* copy direct from output */
					/* minimum length is three */
					/* Align out addr */
					if (!((long)(out - 1 + OFF) & 1)) {
						PUP(out) = PUP(from);
						len--;
					}
					sout = (unsigned short *)(out - OFF);
					if (dist > 2) {
						unsigned short *sfrom;

						sfrom = (unsigned short *)(from -
									   OFF);
						loops = len >> 1;
						do
							PUP(sout) =
								get_unaligned(
									++sfrom);
						while (--loops);
						out = (unsigned char *)sout +
						      OFF;
						from = (unsigned char *)sfrom +
						       OFF;
					} else { /* dist == 1 or dist == 2 */
						unsigned short pat16;

						pat16 = *(sout - 2 + 2 * OFF);
						if (dist == 1)
#if defined(__BIG_ENDIAN)
							pat16 = (pat16 & 0xff) |
								((pat16 & 0xff)
								 << 8);
#elif defined(__LITTLE_ENDIAN)
							pat16 = (pat16 &
								 0xff00) |
								((pat16 &
								  0xff00) >>
								 8);
#else
#error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined
#endif
						loops = len >> 1;
						do
							PUP(sout) = pat16;
						while (--loops);
						out = (unsigned char *)sout +
						      OFF;
					}
					if (len & 1)
						PUP(out) = PUP(from);
				}
			} else if ((op & 64) ==
				   0) { /* 2nd level distance code */
				this = dcode[this.val +
					     (hold & ((1U << op) - 1))];
				goto dodist;
			} else {
				strm->msg   = (char *)"invalid distance code";
				state->mode = BAD;
				break;
			}
		} else if ((op & 64) == 0) { /* 2nd level length code */
			this = lcode[this.val + (hold & ((1U << op) - 1))];
			goto dolen;
		} else if (op & 32) { /* end-of-block */
			Tracevv((stderr, "inflate:         end of block\n"));
			state->mode = TYPE;
			break;
		} else {
			strm->msg   = (char *)"invalid literal/length code";
			state->mode = BAD;
			break;
		}
	} while (in < last && out < end);

	/* return unused bytes (on entry, bits < 8, so in won't go too far back) */
	len = bits >> 3;
	in -= len;
	bits -= len << 3;
	hold &= (1U << bits) -1;

	/* update state and return */
	strm->next_in  = in + OFF;
	strm->next_out = out + OFF;
	strm->avail_in =
		(unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
	strm->avail_out =
		(unsigned)(out < end ? 257 + (end - out) : 257 - (out - end));
	state->hold = hold;
	state->bits = bits;
	return;
}

/*
   inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
   - Using bit fields for code structure
   - Different op definition to avoid & for extra bits (do & for table bits)
   - Three separate decoding do-loops for direct, window, and write == 0
   - Special case for distance > 1 copies to do overlapped load and store copy
   - Explicit branch predictions (based on measured branch probabilities)
   - Deferring match copy and interspersed it with decoding subsequent codes
   - Swapping literal/length else
   - Swapping window/direct else
   - Larger unrolled copy loops (three is about right)
   - Moving len -= 3 statement into middle of loop
 */

#endif /* !ASMINF */
