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components: Fix bit-sel inputs of generic mux/demux when not a power of two #4739

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Merged
grandixximo merged 1 commit into from
Oct 31, 2026
Merged

components: Fix bit-sel inputs of generic mux/demux when not a power of two #4739

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2 changes: 0 additions & 2 deletions docs/src/man/man9/demux_generic.9.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,6 @@ demux-gen.NN.in-[bool/real/sint/uint] ───┤ ─────o o──
changes. This helps to ignore 'noisy' switches.
**demux-gen**.__N__.**sel-bit-**__BB__ bool in (BB=0..bit width of _size_)::
**demux-gen**.__N__.**sel-int** uint in::
The sel-bit pins are only created when the size of the demux_gen
component is an integer power of two.
Together, these determine to which **out**-__MM__ the **in** value is forwarded.
The bit pins are interpreted as binary bits, and the result is simply
added on to the integer pin input. It is expected that either one or
Expand Down
6 changes: 2 additions & 4 deletions docs/src/man/man9/mux_generic.9.adoc
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Expand Up @@ -45,10 +45,8 @@ mux-gen.NN.in-[bool/real/sint/uint]-MM ───┤ ─────o
added on to the integer pin input. It is expected that either one or
the other would normally be used. However, the possibility exists to
use a higher-order bit to "shift" the values set by the integer pin.
The sel-bit pins are only created when the size of the mux_gen
component is an integer power of two. This component (unlike mux16)
does not offer the option of decoding Gray-code, however the same
effect can be achieved by arranging the order of the input values to suit.
This component (unlike mux16) does not offer the option of decoding Gray-code,
however the same effect can be achieved by arranging the order of the input values to suit.
**mux-gen**.__N__.**in-**[**bool**/**real**/**sint**/**uint**]**-**__MM__ variable-type in::
The possible output values that are selected by the selection pins.
**mux-gen**.__N__.**out-**[**bool**/**real**/**sint**/**uint**] variable-type out::
Expand Down
67 changes: 37 additions & 30 deletions src/hal/components/demux_generic.c
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Expand Up @@ -91,7 +91,6 @@ int rtapi_app_main(void){
// Parse the config string
for (i = 0; i < demux->num_insts; i++) {
char c;
int s, p = 0;
demux_inst_t *inst = &demux->insts[i];
inst->in_type = -1;
inst->out_type = -1;
Expand Down Expand Up @@ -176,21 +175,32 @@ int rtapi_app_main(void){
" failed\n");
goto fail0;
}

// Input pins

// if the demux size is a power of 2 then create the bit inputs
s = inst->size;
for(inst->num_bits = 1; (!((s >>= 1) & 1)); inst->num_bits++);
if (s !=1){
inst->num_bits = 0;
} else { //make the bit pins
inst->sel_bit = hal_malloc(inst->num_bits * sizeof(*inst->sel_bit));
for (p = 0; p < inst->num_bits; p++) {
retval = hal_pin_new_bool(comp_id, HAL_IN, &inst->sel_bit[p], 0,
"demux-gen.%02i.sel-bit-%02i", i, p);
if (retval != 0) {
goto fail0;
}
inst->num_bits = 0;
// Count the position of the highest bit set in inst->size-1.
// We know that inst->size >= 2 from tests above. This will work
// for any value, regardless whether it is a power of two or not
// because of the -1 on the size and counting until all bits
// have become zero.
for (int s = inst->size - 1; 0 != s; inst->num_bits++) {
s >>= 1;
}
if (inst->num_bits < 1) {
// This is a safety guard. It should never happen.
rtapi_print_msg(RTAPI_MSG_ERR, "demux_generic: INTERNAL ERROR: num_bits == 0\n");
goto fail0;
}
inst->sel_bit = hal_malloc(inst->num_bits * sizeof(*inst->sel_bit));
if (!inst->sel_bit) {
rtapi_print_msg(RTAPI_MSG_ERR, "demux_generic: ERROR: out of HAL memory\n");
goto fail0;
}
for (int p = 0; p < inst->num_bits; p++) {
retval = hal_pin_new_bool(comp_id, HAL_IN, &inst->sel_bit[p], 0,
"demux-gen.%02i.sel-bit-%02i", i, p);
if (retval != 0) {
goto fail0;
}
}

Expand Down Expand Up @@ -240,7 +250,7 @@ int rtapi_app_main(void){

//output pins
inst->outputs = hal_malloc(inst->size * sizeof(*inst->outputs));
for (p = 0; p < inst->size; p++) {
for (int p = 0; p < inst->size; p++) {
retval = rtapi_snprintf(hal_name, sizeof(hal_name),
"demux-gen.%02i.out-%s-%02i", i, types[inst->out_type], p);
if (retval > HAL_NAME_LEN) {
Expand All @@ -262,40 +272,37 @@ int rtapi_app_main(void){
hal_ready(comp_id);
return 0;

fail0:
fail0:
hal_exit(comp_id);
return -1;

}

// From 'f' to 't' conversion
#define FT(f,t) ((((f) & 0x0f) << 4) + ((t) & 0x0f))

void write_fp(void *arg, long period) {
demux_inst_t *inst = arg;
int i = 0;
rtapi_uint s = 0;
if (inst->num_bits > 0) {
while (i < inst->num_bits) {
s += (hal_get_bool(inst->sel_bit[i]) != 0) << i;
i++;
}
rtapi_sint s = 0;
for (int i = 0; i < inst->num_bits; i++) {
s += (rtapi_sint)hal_get_bool(inst->sel_bit[i]) << i;
}
// if you document it, it's not a bug, it's a feature. Might even be useful
s += hal_get_uint(inst->sel_int);
rtapi_uint u = hal_get_uint(inst->sel_int);
// The calculation here is to prevent signed/unsigned overflow.
s += u > MAX_SIZE ? MAX_SIZE : u;

if (hal_get_bool(inst->suppress) && s == 0)
return;
rtapi_uint timer = hal_get_uint(inst->timer);
if (s != hal_get_uint(inst->selection) && timer < hal_get_uint(inst->debounce)) {
if ((rtapi_uint)s != hal_get_uint(inst->selection) && timer < hal_get_uint(inst->debounce)) {
hal_set_uint(inst->timer, timer + period / 1000);
return;
}

hal_set_uint(inst->selection, s);
hal_set_uint(inst->timer, 0);

if ((rtapi_sint)s >= inst->size)
if (s >= inst->size)
s = inst->size - 1;

switch (FT(inst->in_type, inst->out_type)) {
Expand Down Expand Up @@ -370,6 +377,6 @@ void write_fp(void *arg, long period) {
}

void rtapi_app_exit(void){
//everything is hal_malloc-ed which saves a lot of cleanup here
hal_exit(comp_id);
// everything is hal_malloc-ed which saves a lot of cleanup here
hal_exit(comp_id);
}
66 changes: 36 additions & 30 deletions src/hal/components/mux_generic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,6 @@ int rtapi_app_main(void){
// Parse the config string
for (i = 0; i < mux->num_insts; i++) {
char c;
int s, p = 0;
mux_inst_t *inst = &mux->insts[i];
inst->in_type = -1;
inst->out_type = -1;
Expand Down Expand Up @@ -178,20 +177,30 @@ int rtapi_app_main(void){
}

// Input pins

// if the mux size is a power of 2 then create the bit inputs
s = inst->size;
for(inst->num_bits = 1; (!((s >>= 1) & 1)); inst->num_bits++);
if (s !=1){
inst->num_bits = 0;
} else { //make the bit pins
inst->sel_bit = hal_malloc(inst->num_bits * sizeof(*inst->sel_bit));
for (p = 0; p < inst->num_bits; p++) {
retval = hal_pin_new_bool(comp_id, HAL_IN, &inst->sel_bit[p], 0,
"mux-gen.%02i.sel-bit-%02i", i, p);
if (retval != 0) {
goto fail0;
}
inst->num_bits = 0;
// Count the position of the highest bit set in inst->size-1.
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// We know that inst->size >= 2 from tests above. This will work
// for any value, regardless whether it is a power of two or not
// because of the -1 on the size and counting until all bits
// have become zero.
for (int s = inst->size - 1; 0 != s; inst->num_bits++) {
s >>= 1;
}
if (inst->num_bits < 1) {
// This is a safety guard. It should never happen.
rtapi_print_msg(RTAPI_MSG_ERR, "mux_generic: INTERNAL ERROR: num_bits == 0\n");
goto fail0;
}
inst->sel_bit = hal_malloc(inst->num_bits * sizeof(*inst->sel_bit));
if (!inst->sel_bit) {
rtapi_print_msg(RTAPI_MSG_ERR, "mux_generic: ERROR: out of HAL memory\n");
goto fail0;
}
for (int p = 0; p < inst->num_bits; p++) {
retval = hal_pin_new_bool(comp_id, HAL_IN, &inst->sel_bit[p], 0,
"mux-gen.%02i.sel-bit-%02i", i, p);
if (retval != 0) {
goto fail0;
}
}

Expand All @@ -202,7 +211,7 @@ int rtapi_app_main(void){
}

inst->inputs = hal_malloc(inst->size * sizeof(*inst->inputs));
for (p = 0; p < inst->size; p++) {
for (int p = 0; p < inst->size; p++) {
retval = rtapi_snprintf(hal_name, HAL_NAME_LEN,
"mux-gen.%02i.in-%s-%02i", i, types[inst->in_type], p);
if (retval >= HAL_NAME_LEN) {
Expand Down Expand Up @@ -263,39 +272,36 @@ int rtapi_app_main(void){
hal_ready(comp_id);
return 0;

fail0:
fail0:
hal_exit(comp_id);
return -1;

}

// From 'f' to 't' conversion
#define FT(f,t) ((((f) & 0x0f) << 4) + ((t) & 0x0f))

void write_fp(void *arg, long period) {
mux_inst_t *inst = arg;
int i = 0;
rtapi_uint s = 0;
if (inst->num_bits > 0) {
while (i < inst->num_bits) {
s += (hal_get_bool(inst->sel_bit[i]) != 0) << i;
i++;
}
rtapi_sint s = 0;
for (int i = 0; i < inst->num_bits; i++) {
s += (rtapi_sint)hal_get_bool(inst->sel_bit[i]) << i;
}
// if you document it, it's not a bug, it's a feature. Might even be useful
s += hal_get_uint(inst->sel_int);
rtapi_uint u = hal_get_uint(inst->sel_int);
// The calculation here is to prevent signed/unsigned overflow.
s += u > MAX_SIZE ? MAX_SIZE : u;

if (hal_get_bool(inst->suppress) && s == 0)
return;
if (s != hal_get_uint(inst->selection) && hal_get_uint(inst->timer) < hal_get_uint(inst->debounce)) {
if ((rtapi_uint)s != hal_get_uint(inst->selection) && hal_get_uint(inst->timer) < hal_get_uint(inst->debounce)) {
hal_set_uint(inst->timer, hal_get_uint(inst->timer) + period / 1000);
return;
}

hal_set_uint(inst->selection, s);
hal_set_uint(inst->timer, 0);

if ((rtapi_sint)s >= inst->size)
if (s >= inst->size)
s = inst->size - 1;

switch (FT(inst->in_type, inst->out_type)) {
Expand Down Expand Up @@ -370,6 +376,6 @@ void write_fp(void *arg, long period) {
}

void rtapi_app_exit(void){
//everything is hal_malloc-ed which saves a lot of cleanup here
hal_exit(comp_id);
// everything is hal_malloc-ed which saves a lot of cleanup here
hal_exit(comp_id);
}
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