luke
/
iverilog
mirror of https://github.com/steveicarus/iverilog.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Make the procedural shifts work with undefined shift values. 

This patch adds code to check for an undefined shift value in
the procedural opcodes. When an undefined value is found 'bx
is returned.
This commit is contained in:
Cary R 2008-12-14 12:46:23 -08:00 committed by Stephen Williams
parent 4f4191ecdd
commit 8cd50c163b
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
vvp/vthread.cc
View File

@ -4126,7 +4126,11 @@ bool of_SHIFTL_I0(vthread_t thr, vvp_code_t cp)
assert(base >= 4);
thr_check_addr(thr, base+wid-1);
if (shift >= wid) {
if (thr_get_bit(thr, 4) == BIT4_1) {
// The result is 'bx if the shift amount is undefined.
vvp_vector4_t tmp (wid, BIT4_X);
thr->bits4.set_vec(base, tmp);
} else if (shift >= wid) {
// Shift is so far that all value is shifted out. Write
// in a constant 0 result.
vvp_vector4_t tmp (wid, BIT4_0);
@ -4157,7 +4161,11 @@ bool of_SHIFTR_I0(vthread_t thr, vvp_code_t cp)
unsigned wid = cp->number;
unsigned long shift = thr->words[0].w_int;
if (shift > 0) {
if (thr_get_bit(thr, 4) == BIT4_1) {
// The result is 'bx if the shift amount is undefined.
vvp_vector4_t tmp (wid, BIT4_X);
thr->bits4.set_vec(base, tmp);
} else if (shift > 0) {
unsigned idx;
for (idx = 0 ; (idx+shift) < wid ; idx += 1) {
unsigned src = base + idx + shift;
@ -4177,7 +4185,11 @@ bool of_SHIFTR_S_I0(vthread_t thr, vvp_code_t cp)
unsigned long shift = thr->words[0].w_int;
vvp_bit4_t sign = thr_get_bit(thr, base+wid-1);
if (shift >= wid) {
if (thr_get_bit(thr, 4) == BIT4_1) {
// The result is 'bx if the shift amount is undefined.
vvp_vector4_t tmp (wid, BIT4_X);
thr->bits4.set_vec(base, tmp);
} else if (shift >= wid) {
for (unsigned idx = 0 ; idx < wid ; idx += 1)
thr_put_bit(thr, base+idx, sign);