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Make tgt-vvp insert a BUFT for pulldown devices. 

A BUFT is needed to allow a force to override the pull value. This had
already been done for pullup devices, so factor out the common code and
use for both pullup and pulldown.
This commit is contained in:
Martin Whitaker 2013-10-26 12:22:14 +01:00
parent d291e2b23d
commit 36c91491cc
1 changed files with 54 additions and 84 deletions
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138
tgt-vvp/draw_net_input.c
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@ -225,6 +225,58 @@ static void str_repeat(char*buf, const char*str, unsigned rpt)
}
}
/*
* This function draws a BUFT to drive a net pullup or pulldown value.
* If the drive strength is strong we can draw a C4<> constant as the
* pull value, otherwise we need to draw a C8<> constant.
*/
static char* draw_net_pull(ivl_net_logic_t lptr, ivl_drive_t drive, char*level)
{
char*result;
char tmp[32];
if (drive == IVL_DR_STRONG) {
size_t result_len = 5 + ivl_logic_width(lptr);
result = malloc(result_len);
char*dp = result;
strcpy(dp, "C4<");
dp += strlen(dp);
str_repeat(dp, level, ivl_logic_width(lptr));
dp += ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
} else {
char val[4];
size_t result_len = 5 + 3*ivl_logic_width(lptr);
result = malloc(result_len);
char*dp = result;
val[0] = "01234567"[drive];
val[1] = val[0];
val[2] = level[0];
val[3] = 0;
strcpy(dp, "C8<");
dp += strlen(dp);
str_repeat(dp, val, ivl_logic_width(lptr));
dp += 3*ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
}
/* Make the constant an argument to a BUFZ, which is
what we use to drive the PULLed value. */
fprintf(vvp_out, "L_%p .functor BUFT 1, %s, C4<0>, C4<0>, C4<0>;\n",
lptr, result);
snprintf(tmp, sizeof tmp, "L_%p", lptr);
result = realloc(result, strlen(tmp)+1);
strcpy(result, tmp);
return result;
}
/*
* This function takes a nexus and looks for an input functor. It then
* draws to the output a string that represents that functor. What we
@ -251,94 +303,12 @@ static char* draw_net_input_drive(ivl_nexus_t nex, ivl_nexus_ptr_t nptr)
return strdup(draw_net_input(ivl_logic_pin(lptr, 1)));
} while(0);
/* If this is a pulldown device, then there is a single pin
that drives a constant value to the entire width of the
vector. The driver normally drives a pull0 value, so a C8<>
constant is appropriate, but if the drive is really strong,
then we can draw a C4<> constant instead. */
if (lptr && (ivl_logic_type(lptr) == IVL_LO_PULLDOWN)) {
if (ivl_nexus_ptr_drive0(nptr) == IVL_DR_STRONG) {
size_t result_len = ivl_logic_width(lptr) + 5;
char*result = malloc(result_len);
char*dp = result;
strcpy(dp, "C4<");
dp += strlen(dp);
str_repeat(dp, "0", ivl_logic_width(lptr));
dp += ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
return result;
} else {
char val[4];
size_t result_len = 3*ivl_logic_width(lptr) + 5;
char*result = malloc(result_len);
char*dp = result;
val[0] = "01234567"[ivl_nexus_ptr_drive0(nptr)];
val[1] = val[0];
val[2] = '0';
val[3] = 0;
strcpy(dp, "C8<");
dp += strlen(dp);
str_repeat(dp, val, ivl_logic_width(lptr));
dp += 3*ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
return result;
}
return draw_net_pull(lptr, ivl_nexus_ptr_drive0(nptr), "0");
}
if (lptr && (ivl_logic_type(lptr) == IVL_LO_PULLUP)) {
char*result;
char tmp[32];
if (ivl_nexus_ptr_drive1(nptr) == IVL_DR_STRONG) {
size_t result_len = 5 + ivl_logic_width(lptr);
result = malloc(result_len);
char*dp = result;
strcpy(dp, "C4<");
dp += strlen(dp);
str_repeat(dp, "1", ivl_logic_width(lptr));
dp += ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
} else {
char val[4];
size_t result_len = 5 + 3*ivl_logic_width(lptr);
result = malloc(result_len);
char*dp = result;
val[0] = "01234567"[ivl_nexus_ptr_drive1(nptr)];
val[1] = val[0];
val[2] = '1';
val[3] = 0;
strcpy(dp, "C8<");
dp += strlen(dp);
str_repeat(dp, val, ivl_logic_width(lptr));
dp += 3*ivl_logic_width(lptr);
*dp++ = '>';
*dp = 0;
assert(dp >= result);
assert((unsigned)(dp - result) <= result_len);
}
/* Make the constant an argument to a BUFZ, which is
what we use to drive the PULLed value. */
fprintf(vvp_out, "L_%p .functor BUFT 1, %s, C4<0>, C4<0>, C4<0>;\n",
lptr, result);
snprintf(tmp, sizeof tmp, "L_%p", lptr);
result = realloc(result, strlen(tmp)+1);
strcpy(result, tmp);
return result;
return draw_net_pull(lptr, ivl_nexus_ptr_drive1(nptr), "1");
}
if (lptr && (nptr_pin == 0)) {