diff options
Diffstat (limited to 'src/pc80')
| -rw-r--r-- | src/pc80/mc146818rtc.c | 160 |
1 files changed, 36 insertions, 124 deletions
diff --git a/src/pc80/mc146818rtc.c b/src/pc80/mc146818rtc.c index 55f161f29e..0baa389c1f 100644 --- a/src/pc80/mc146818rtc.c +++ b/src/pc80/mc146818rtc.c @@ -197,69 +197,41 @@ void rtc_init(int invalid) #if USE_OPTION_TABLE == 1 -/* - * Functions to save/return values stored in the 256byte cmos. - * - * To be able to use space maximally we want to only store as many bits as - * needed, and not be limited by byte boundaries. We therefor clamp the size - * down to an unsigned int. Since the values that we are allowed to touch are - * either an enum or a hexadecimal value, this size should suit most purposes. - * - * These two functions are doing bitshifting, and are therefor a bit - * nontrivial. To understand these operations, first read the ones outside the - * loop. The ones inside the loop are just adding i to the same calculations, - * with the shift twice inverted, as negative shifts aren't nice. - */ -static unsigned int -get_cmos_value(int bit, int length) -{ - unsigned int tmp; - int i; - - /* negative left shift --> right shift */ - tmp = cmos_read(bit / 8) >> (bit % 8); - - for (i = 1; (8 * i) < ((bit % 8) + length); i++) - tmp |= cmos_read((bit / 8) + i) << ((8 * i) - (bit % 8)); - - /* 1 << 32 - 1 isn't cool inside an int */ - if (length != 32) - tmp &= (1 << length) - 1; - - return tmp; -} - -static void -set_cmos_value(int bit, int length, unsigned int value) +/* This routine returns the value of the requested bits + input bit = bit count from the beginning of the cmos image + length = number of bits to include in the value + ret = a character pointer to where the value is to be returned + output the value placed in ret + returns 0 = successful, -1 = an error occurred +*/ +static int get_cmos_value(unsigned long bit, unsigned long length, void *vret) { - unsigned int mask; - unsigned char cmos; - int i; - - /* 1 << 32 - 1 isn't cool inside an int */ - if (length != 32) - mask = (1 << length) - 1; - else - mask = -1; - - value &= mask; - - /* negative right shifts --> left shifts */ - cmos = cmos_read(bit / 8); - cmos &= ~(mask << (bit % 8)); - cmos |= value << (bit % 8); - cmos_write(cmos, bit / 8); - - for (i = 1; (8 * i) < ((bit % 8) + length); i++) { - cmos = cmos_read((bit / 8) + i); - cmos &= ~(mask >> ((8 * i) - (bit % 8))); - cmos |= value >> ((8 * i) - (bit % 8)); - cmos_write(cmos, (bit / 8) + i); + unsigned char *ret; + unsigned long byte,byte_bit; + unsigned long i; + unsigned char uchar; + + /* The table is checked when it is built to ensure all + values are valid. */ + ret = vret; + byte=bit/8; /* find the byte where the data starts */ + byte_bit=bit%8; /* find the bit in the byte where the data starts */ + if(length<9) { /* one byte or less */ + uchar = cmos_read(byte); /* load the byte */ + uchar >>= byte_bit; /* shift the bits to byte align */ + /* clear unspecified bits */ + ret[0] = uchar & ((1 << length) -1); + } + else { /* more that one byte so transfer the whole bytes */ + for(i=0;length;i++,length-=8,byte++) { + /* load the byte */ + ret[i]=cmos_read(byte); + } } + return 0; } -int -get_option(char *name, unsigned int *value) +int get_option(void *dest, char *name) { extern struct cmos_option_table option_table; struct cmos_option_table *ct; @@ -269,7 +241,7 @@ get_option(char *name, unsigned int *value) /* Figure out how long name is */ namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); - + /* find the requested entry record */ ct=&option_table; ce=(struct cmos_entries*)((unsigned char *)ct + ct->header_length); @@ -284,72 +256,12 @@ get_option(char *name, unsigned int *value) printk_err("ERROR: No cmos option '%s'\n", name); return(-2); } - - if (ce->length > 32) { - printk_err("ERROR: cmos option '%s' is too large.\n", name); - return -3; - } - - - *value = get_cmos_value(ce->bit, ce->length); - + + if(get_cmos_value(ce->bit, ce->length, dest)) + return(-3); if(!rtc_checksum_valid(LB_CKS_RANGE_START, - LB_CKS_RANGE_END,LB_CKS_LOC)) + LB_CKS_RANGE_END,LB_CKS_LOC)) return(-4); return(0); } - -int -set_option(char *name, unsigned int value) -{ - extern struct cmos_option_table option_table; - struct cmos_option_table *ct; - struct cmos_entries *ce; - size_t namelen; - int found = 0; - - /* Figure out how long name is */ - namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); - - /* find the requested entry record */ - ct = &option_table; - ce = (struct cmos_entries*) ((unsigned char *) ct + ct->header_length); - - for(;ce->tag==LB_TAG_OPTION; - ce=(struct cmos_entries*)((unsigned char *)ce + ce->size)) { - if (memcmp(ce->name, name, namelen) == 0) { - found=1; - break; - } - } - - if (!found) { - printk_err("ERROR: Unknown cmos option '%s'\n", name); - return(-2); - } - - if (ce->length > 32) { - printk_err("ERROR: cmos option '%s' is too large.\n", name); - return -3; - } - - set_cmos_value(ce->bit, ce->length, value); - - /* We should not update the checksum here. */ - - return 0; -} -#else -int -get_option(char *name, unsigned int *value) -{ - return -2; -} - -int -set_option(char *name, unsigned int value) -{ - return -2; -} - #endif /* USE_OPTION_TABLE */ |