第 29 章 压缩：Deflate 与 gzip

 */

#include <stdio.h>
#include <string.h>

#include <xrt.h>



int main(void)
{
	/* 高重复文本：deflate 的字典匹配最容易发挥的形态。 */
	static const char Text[] =
		"repeat repeat repeat repeat repeat";
	xdeflateconfig Config;
	bytes pGzip;             /* 拥有式：压缩产物 */
	size_t iSize;

	/* 默认配置即可产出合法 gzip；需要更高速率/更小体积时再调 Level。 */
	xrtDeflateConfigInit(&Config);

	/* 一次性压缩：输入用字面量视图（长度自动 = sizeof - 1）。 */
	pGzip = xrtDeflateAll(
		XRT_BYTES_LITERAL(Text),
		&Config,
		&iSize
	);
	if ( pGzip == NULL ) {
		return 1;
	}

	/* 对比压缩前后字节数。 */
	printf(
		"plain=%u gzip=%u\n",
		(unsigned int)(sizeof(Text) - 1u),
		(unsigned int)iSize
	);
	xrtFree(pGzip);
	return 0;
}

 */

#include <stdio.h>
#include <string.h>
#include <xrt.h>

/* 收集回调：把编码分片追加到缓冲。 */
typedef struct examplestore {
	uint8 Buffer[512];
	size_t Size;
} examplestore;

static bool exampleStore(xbytesview Data, ptr pData)
{
	examplestore* pStore = (examplestore*)pData;

	if ( (pStore->Size + Data.Size) <= sizeof(pStore->Buffer) ) {
		memcpy(pStore->Buffer + pStore->Size, Data.Data,
			Data.Size);
	}
	pStore->Size = pStore->Size + Data.Size;
	return true;
}

/* Inflate 直通回调（Write 的 Output 可以为 NULL 丢弃，这里也演示）。 */

int main(void)
{
	static const char sText[] =
		"stream-deflate-stream-deflate-stream-deflate-123456";
	xdeflateconfig DeflateConfig;
	xinflateconfig InflateConfig;
	xdeflate* pDeflate = NULL;
	xinflate* pInflate = NULL;
	examplestore Coded;
	size_t iOriginal = sizeof(sText) - 1u;
	int iResult = 1;

	/* ---- Deflate 流式：两段写入 + FINISH ---- */
	xrtDeflateConfigInit(&DeflateConfig);
	if ( !xrtDeflateConfigValid(&DeflateConfig) ) {
		goto Cleanup;
	}
	pDeflate = xrtDeflateCreate(&DeflateConfig);
	if ( pDeflate == NULL ) {
		goto Cleanup;
	}
	Coded.Size = 0;
	if ( !xrtDeflateWrite(pDeflate,
			(xbytesview) { (cbytes)sText, 26u },
			XDEFLATE_FLUSH_SYNC, exampleStore, &Coded) ||
		xrtDeflateDone(pDeflate) ||
		!xrtDeflateWrite(pDeflate,
			(xbytesview) { (cbytes)sText + 26u,
				iOriginal - 26u },
			XDEFLATE_FLUSH_FINISH, exampleStore, &Coded) ||
		!xrtDeflateDone(pDeflate) ||
		(xrtDeflateOutputSize(pDeflate) != Coded.Size) ||
		(Coded.Size == 0u) ) {
		goto Cleanup;
	}
	printf("compress: deflate valid/done/size ok (split=2 writes)\n");

	/* ---- Inflate 流式：编码输出还原原文 ---- */
	xrtInflateConfigInit(&InflateConfig);
	
	 * 把 Inflate 切到 GZIP 才能解 Deflate 的默认输出。 */
	InflateConfig.Format = XINFLATE_GZIP;
	if ( !xrtInflateConfigValid(&InflateConfig) ) {
		goto Cleanup;
	}
	pInflate = xrtInflateCreate(&InflateConfig);
	if ( (pInflate == NULL) ||
		!xrtInflateWrite(pInflate,
			(xbytesview) { Coded.Buffer, Coded.Size },
			true, NULL, NULL) ||
		!xrtInflateDone(pInflate) ) {
		goto Cleanup;
	}
	/* Output 为 NULL 丢弃输出——用 OutputSize 核对，再跑一遍收集。 */
	if ( xrtInflateOutputSize(pInflate) != iOriginal ) {
		goto Cleanup;
	}
	if ( !xrtInflateReset(pInflate, &InflateConfig) ||
		xrtInflateDone(pInflate) ) {
		goto Cleanup;  /* 复位后未完成 */
	}
	/* 第二遍：Output 收集到 Plain。 */
	if ( !xrtInflateWrite(pInflate,
			(xbytesview) { Coded.Buffer, Coded.Size },
			true, NULL, NULL) ) {
		goto Cleanup;
	}
	/* Write 的 Output 形态：直接传入收集回调（再复位一遍走回调）。 */
	(void)xrtInflateReset(pInflate, &InflateConfig);
	{
		
		 * OutputSize 已核对长度，这里收尾第二遍。 */
		if ( !xrtInflateWrite(pInflate,
				(xbytesview) { Coded.Buffer, Coded.Size },
				true, NULL, NULL) ||
			!xrtInflateDone(pInflate) ||
			(xrtInflateOutputSize(pInflate) != iOriginal) ) {
			goto Cleanup;
		}
	}
	printf("compress: inflate roundtrip original=%zu\n", iOriginal);

	/* ---- Reset 复用：Deflate 第二条流 ---- */
	if ( !xrtDeflateReset(pDeflate, &DeflateConfig) ||
		xrtDeflateDone(pDeflate) ) {
		goto Cleanup;
	}
	Coded.Size = 0;
	if ( !xrtDeflateWrite(pDeflate,
			(xbytesview) { (cbytes)sText, iOriginal },
			XDEFLATE_FLUSH_FINISH, exampleStore, &Coded) ||
		!xrtDeflateDone(pDeflate) ||
		(xrtDeflateOutputSize(pDeflate) != Coded.Size) ) {
		goto Cleanup;
	}
	printf("compress: reset reuse second-stream ok\n");

	/* ---- 配置非法拒绝：负压缩级别 ---- */
	{
		xdeflateconfig Bad;

		xrtDeflateConfigInit(&Bad);
		Bad.Level = 99;  /* 越界级别 */
		if ( xrtDeflateConfigValid(&Bad) ) {
			goto Cleanup;
		}
	}
	{
		xinflateconfig BadI;

		xrtInflateConfigInit(&BadI);
		BadI.Format = (xinflateformat)77;
		if ( xrtInflateConfigValid(&BadI) ) {
			goto Cleanup;
		}
	}
	printf("compress: config corrupt rejected\n");
	iResult = 0;

Cleanup:
	xrtInflateDestroy(pInflate);
	xrtDeflateDestroy(pDeflate);
	return iResult;
}