On Sat, 28 Feb 2009 19:24:38 -0700
"Weddington, Eric" <ewedding...@cso.atmel.com> wrote:
> You wouldn't need *nested* ifs, but an if-else-if structure, or better yet, a
> table of function pointers, also known as a dispatch table. Each method
> depends on the type of data that you're switching on.
I switch on an unsigned byte, with contiguous values (0-24).
A Function table sounds elegant to my ear, but it would mean 25
functions ! In my case the work is done in-situ, within the switch
statement, as it's takes only 2 or 3 statements to process a givne
"case". Using functions would be both overkill and overwhelming to
manage I think !! ;-)
I pasted my switch statement below for the curious.
--
Vince
void var_format(char *buff, uint8_t var_num)
{
uint16_t tmp16;
uint32_t tmp32;
int16_t tmpS16;
char Yes[] = " Yes";
char No[] = " No";
char Unknown[] = "-\?\?\?-";
switch (var_num)
{
case ECU_COOLANT:
{// (N * 0.75) - 40 DB41
-40 to +150 °C
tmpS16 = (int16_t)(KLineFrameM1[41]) * 3 / 4 - 40;
var_format_S16(buff, tmpS16, 0);
break;
}
case ECU_ENGINE_SPEED:
{// MSB:LSB DB12:13
0 to 9999 RPM
ATOMIC_BLOCK(ATOMIC_FORCEON)
{
tmp16 = ((uint16_t)KLineFrameM1[12] << 8) +
(uint16_t)KLineFrameM1[13];
}
var_format_S16(buff, (int16_t)tmp16, 0);
break;
}
case ECU_ROAD_SPEED:
{// DB14 uint8_t MPH
var_format_byte(buff, KLineFrameM1[8]);
break;
}
case ECU_BARO_AIR_PRESSURE:
{// ((N-128)/100)+1 DB24
-0.28 to +2.27 Bar
tmpS16 = (int16_t)(KLineFrameM1[24]) - 28;
var_format_S16(buff, tmpS16, 2);
break;
}
case ECU_MAP_PRESSURE:
{// ((N-130)/100)+1 DB25 -0.30
to +2.25 Bar
tmpS16 = (int16_t)(KLineFrameM1[25]) - 30;
var_format_S16(buff, tmpS16, 2);
break;
}
case ECU_MAT_TEMP:
{// (N * 0.75) - 40 DB42
-40 to +150 °C
tmpS16 = (int16_t)(KLineFrameM1[42]) * 3 / 4 - 40;
var_format_S16(buff, tmpS16, 0);
break;
}
case ECU_THROTTLE_POSITION:
{// N / 2.55 DB27
0 to 100 %
tmp16 = (uint16_t)KLineFrameM1[27] * 100 / 255;
var_format_byte(buff, (uint8_t)tmp16);
break;
}
case ECU_ENGINE_LOAD:
{// DB36 0 - 100 %
var_format_byte(buff, KLineFrameM1[36]);
break;
}
case ECU_KNOCK_COUNT:
{// DB43 uint8_t
var_format_byte(buff, KLineFrameM1[43]);
break;
}
case ECU_KNOCK_RETARD:
{// (N * 45) / 255 DB44
0 to 45 Deg
tmp16 = (uint16_t)KLineFrameM1[44] * 90 / 51;
var_format_S16(buff, (int16_t)tmp16, 1);
break;
}
case ECU_SPARK_ADVANCE:
{// (N * 9000)/256 MSB:LSB DB39:40 0.00 Degrees
ATOMIC_BLOCK(ATOMIC_FORCEON)
{
tmp16 = ((uint16_t)KLineFrameM1[39] << 8) +
(uint16_t)KLineFrameM1[40];
}
tmp32 = (uint32_t)tmp16 * 9000 / 256;
var_format_S16(buff, (int16_t)tmp32, 2);
break;
}
case ECU_BOOST_DC:
{// DB31 uint8_t or %, don't know
var_format_byte(buff, KLineFrameM1[31]);
break;
}
case ECU_MAIN_INJ_DC:
{// DB45 uint8_t
var_format_byte(buff, KLineFrameM1[45]);
break;
}
case ECU_SECONDARY_INJ_DC:
{// DB37 uint8_t
var_format_byte(buff, KLineFrameM1[37]);
break;
}
case ECU_AF_RATIO:
{// N * 10 DB47
0.0 to 25.5
var_format_S16(buff, (int16_t)KLineFrameM1[47], 1);
break;
}
case ECU_IAC_POSITION:
{// DB23 0 to 170
var_format_byte(buff, KLineFrameM1[23]);
break;
}
case ECU_COOLANT_START:
{// (N * 0.75) - 40 DB9 -40 to +150 °C
tmpS16 = (int16_t)(KLineFrameM1[9]) * 3 / 4 - 40;
var_format_S16(buff, tmpS16, 0);
break;
}
case ECU_DESIRED_IDLE:
{// N * 12.5 DB11
0 to 3187 RPM
tmp16 = (uint16_t)(KLineFrameM1[11]) * 25 / 2;
var_format_S16(buff, (int16_t)tmp16, 0);
break;
}
case ECU_RAW_ADC_COOLANT:
{// DB8 uint8_t
var_format_byte(buff, KLineFrameM1[8]);
break;
}
case ECU_RAW_ADC_THROTTLE:
{// DB10 uint8_t
var_format_byte(buff, KLineFrameM1[10]);
break;
}
case ECU_RAW_ADC_MAT:
{// DB29 uint8_t
var_format_byte(buff, KLineFrameM1[29]);
break;
}
case ECU_CLOSED_LOOP_MODE:
{// DB63 & 0x80 YES/NO
if ( KLineFrameM1[63] & 0x80 )
strcpy(buff, Yes);
else
strcpy(buff, No);
break;
}
case ECU_AIR_CON_DEMAND:
{// DB6 & 0x08 YES/NO
if ( KLineFrameM1[6] & 0x08 )
strcpy(buff, Yes);
else
strcpy(buff, No);
break;
}
case ECU_AIR_CON_ENGAGED:
{// DB7 & 0x01 YES/NO
if ( KLineFrameM1[7] & 0x01 )
strcpy(buff, Yes);
else
strcpy(buff, No);
break;
}
case ECU_FAN_RUNNING:
{// DB7 & 0x04 YES/NO
if ( KLineFrameM1[7] & 0x04 )
strcpy(buff, Yes);
else
strcpy(buff, No);
break;
}
default:
strcpy(buff, Unknown);
}
}
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