stricmp.c

一款MP3 Player Firmware 的原代码,非常有参考价值

#include <ctype.h>

#include "as31glue.h"
#include "stricmp.h"


xdata char * data strcpy_asm_src_addr;


#pragma LESS_PEDANTIC


// Fast stricmp, returns -1 if *a < *b, 0 if equal, +1 if *a > *b
// Call this as:
//   stricmp(xdata char *a, xdata char *b)

char stricmp_asm(xdata char *a) _naked
{
	a;
	_asm
	inc	AUXR1		// switch to DPTR1 & load w/ "b"
	mov	dpl, _strcpy_asm_src_addr+0
	mov	dph, _strcpy_asm_src_addr+1
	inc	AUXR1		// switch to "a" pointer
stricmp_loop:
	inc	AUXR1		// switch to "b" pointer
	movx	a, @dptr	// fetch byte from "b" string
	inc	dptr
	cjne	a, #97, stricmp_b_1
stricmp_b_1:
	jc	stricmp_b
	cjne	a, #123, stricmp_b_2
stricmp_b_2:
	jnc	stricmp_b
	add	a, #224
stricmp_b:
	mov	b, a		// keep uppercase of *b in b register

	inc	AUXR1		// switch to "a" pointer
	movx	a, @dptr	// fetch byte from "a" string
	inc	dptr
	cjne	a, #97, stricmp_a_1
stricmp_a_1:
	jc	stricmp_a
	cjne	a, #123, stricmp_a_2
stricmp_a_2:
	jnc	stricmp_a
	add	a, #224
stricmp_a:			// acc has uppercase of *a
	cjne	a, b, stricmp_a_ne_b
	jnz	stricmp_loop
stricmp_a_eq_b:
	mov	dpl, #0
	ret
stricmp_a_ne_b:			// not equal, C bit tells which was greater
	jnc	stricmp_a_gt_b
stricmp_a_lt_b:
	mov	dpl, #-1
	ret
stricmp_a_gt_b:
	mov	dpl, #1
	ret
	_endasm;
}


// Fast memset.  Fills a block of memory with a particular byte.
// Call this as:
//   memset(xdata void *ptr, unsigned char ch, unsigned char length)

void memset_asm(xdata void *ptr) _naked
{
	ptr;
	_asm
	mov	b, r0
	mov	r0, _strcpy_asm_src_addr
	mov	a, (_strcpy_asm_src_addr + 1)
memset_loop:
	movx	@dptr, a
	inc	dptr
	djnz	r0, memset_loop
	mov	r0, b
	ret
	_endasm;
}


// Fast string initialization.  Fills a string with a character
// and put a null termination on the end.
// Call this as:
//   string_init(xdata char *str, char ch, unsigned char sizeof(str));


void string_init_asm(xdata char *str) _naked
{
	str;
	_asm
	lcall	_memset_asm
	clr	a
	movx	@dptr, a
	ret
	_endasm;
}


// copy string, but don't copy more than len-1 bytes and always
// null terminate (note, this one always gives a null termination
// on the end, unlike the "standard" strncmp in many C libraries)

void strncpy_asm(xdata char *dest_addr, xdata unsigned char len) _naked
{
	dest_addr;	// passed in DPTR
	len;		// passed @ _strncpy_asm_PARM_2
	_asm
	inc	AUXR1
	mov	dptr, #_strncpy_asm_PARM_2
	movx	a, @dptr
	dec	a
	mov	b, a
	sjmp	fast_strcpy_entry
	_endasm;
}



void strcpy_asm(xdata char *dest_addr)
{
	dest_addr;	// supress compiler's unused variable warning
	_asm
	// on entry, DPTR0 has destination addr
	inc	AUXR1		// switch to DPTR1 & load w/ src addr
	mov	b, #255
fast_strcpy_entry:
	mov	dpl, _strcpy_asm_src_addr+0
	mov	dph, _strcpy_asm_src_addr+1
fast_strcpy_loop:
	movx	a, @dptr	// read source
	jz	fast_strcpy_done
	inc	dptr
	inc	AUXR1		// switch to DPTR0 (dest_addr)
	movx	@dptr, a	// write destination
	inc	dptr
	inc	AUXR1		// switch to DPTR1 (src_addr)
	djnz	b, fast_strcpy_loop
fast_strcpy_done:
	inc	AUXR1		// switch to DPTR0 (dest_addr)
	clr	a
	movx	@dptr, a	// don't forget to null-terminate the copy
	_endasm;
}


unsigned int strlen_asm(xdata char *str)
{
	str;
	_asm
	inc	AUXR1
	mov	dptr, #0
	inc	AUXR1
strlen_asm_loop:
	movx	a, @dptr
	jz	strlen_asm_end
	inc	dptr
	inc	AUXR1
	inc	dptr
	inc	AUXR1
	sjmp	strlen_asm_loop
strlen_asm_end:
	inc	AUXR1
	_endasm;
}


unsigned char str_is_dot_mp3(xdata unsigned char *str)
{
	str;
	_asm
	movx	a, @dptr	// fetch first byte
	cjne	a, #0x2E, str_is_not_dot_mp3	// check '.'
	inc	dptr
	movx	a, @dptr	// fetch second byte
	orl	a, #0x20
	cjne	a, #0x6D, str_is_not_dot_mp3	// check 'm'
	inc	dptr
	movx	a, @dptr	// fetch third byte
	orl	a, #0x20
	cjne	a, #0x70, str_is_not_dot_mp3	// check 'p'
	inc	dptr
	movx	a, @dptr	// fetch fourth byte
	cjne	a, #0x33, str_is_not_dot_mp3	// check '3'
	inc	dptr
	movx	a, @dptr	// fetch last byte
	jnz	str_is_not_dot_mp3
	mov	dpl, #1
	ret
str_is_not_dot_mp3:
	mov	dpl, #0
	ret
	_endasm;
}

unsigned char str_is_dot_m3u(xdata unsigned char *str)
{
	str;
	_asm
	movx	a, @dptr	// fetch first byte
	cjne	a, #0x2E, str_is_not_dot_m3u	// check '.'
	inc	dptr
	movx	a, @dptr	// fetch second byte
	orl	a, #0x20
	cjne	a, #0x6D, str_is_not_dot_m3u	// check 'm'
	inc	dptr
	movx	a, @dptr	// fetch third byte
	orl	a, #0x20
	cjne	a, #0x33, str_is_not_dot_m3u	// check '3'
	inc	dptr
	movx	a, @dptr	// fetch fourth byte
	cjne	a, #0x75, str_is_not_dot_m3u	// check 'u'
	inc	dptr
	movx	a, @dptr	// fetch last byte
	jnz	str_is_not_dot_m3u
	mov	dpl, #1
	ret
str_is_not_dot_m3u:
	mov	dpl, #0
	ret
	_endasm;
}