diff options
Diffstat (limited to 'kernel/byterun')
| -rw-r--r-- | kernel/byterun/coq_interp.c | 39 | ||||
| -rw-r--r-- | kernel/byterun/coq_uint63_native.h | 53 |
2 files changed, 41 insertions, 51 deletions
diff --git a/kernel/byterun/coq_interp.c b/kernel/byterun/coq_interp.c index 2293ae9dfd..e38d458b36 100644 --- a/kernel/byterun/coq_interp.c +++ b/kernel/byterun/coq_interp.c @@ -1374,40 +1374,11 @@ value coq_interprete Instruct (CHECKDIV21INT63) { print_instr("DIV21INT63"); CheckInt3(); - /* spiwack: takes three int31 (the two first ones represent an - int62) and performs the euclidian division of the - int62 by the int31 */ - /* TODO: implement this - bigint = UI64_of_value(accu); - bigint = I64_or(I64_lsl(bigint, 31),UI64_of_value(*sp++)); - uint64 divisor; - divisor = UI64_of_value(*sp++); - Alloc_small(accu, 2, 1); */ /* ( _ , arity, tag ) */ - /* if (I64_is_zero (divisor)) { - Field(accu, 0) = 1; */ /* 2*0+1 */ - /* Field(accu, 1) = 1; */ /* 2*0+1 */ - /* } - else { - uint64 quo, mod; - I64_udivmod(bigint, divisor, &quo, &mod); - Field(accu, 0) = value_of_uint32(I64_to_int32(quo)); - Field(accu, 1) = value_of_uint32(I64_to_int32(mod)); - } */ - int b; - Uint63_eq0(b, sp[1]); - if (b) { - AllocPair(); - Field(accu, 0) = sp[1]; - Field(accu, 1) = sp[1]; - } - else { - Uint63_div21(accu, sp[0], sp[1], sp); - sp[1] = sp[0]; - Swap_accu_sp; - AllocPair(); - Field(accu, 0) = sp[1]; - Field(accu, 1) = sp[0]; - } + Uint63_div21(accu, sp[0], sp[1], &(sp[1])); + Swap_accu_sp; + AllocPair(); + Field(accu, 0) = sp[1]; + Field(accu, 1) = sp[0]; sp += 2; Next; } diff --git a/kernel/byterun/coq_uint63_native.h b/kernel/byterun/coq_uint63_native.h index d431dc1e5c..8dee0d69d3 100644 --- a/kernel/byterun/coq_uint63_native.h +++ b/kernel/byterun/coq_uint63_native.h @@ -109,37 +109,56 @@ value uint63_mulc(value x, value y, value* h) { #define lt128(xh,xl,yh,yl) (uint63_lt(xh,yh) || (uint63_eq(xh,yh) && uint63_lt(xl,yl))) #define le128(xh,xl,yh,yl) (uint63_lt(xh,yh) || (uint63_eq(xh,yh) && uint63_leq(xl,yl))) -value uint63_div21(value xh, value xl, value y, value* q) { - xh = (uint64_t)xh >> 1; - xl = ((uint64_t)xl >> 1) | ((uint64_t)xh << 63); - xh = (uint64_t)xh >> 1; +#define maxuint63 ((uint64_t)0x7FFFFFFFFFFFFFFF) +/* precondition: y <> 0 */ +/* outputs r and sets ql to q % 2^63 s.t. x = q * y + r, r < y */ +static value uint63_div21_aux(value xh, value xl, value y, value* ql) { + xh = uint63_of_value(xh); + xl = uint63_of_value(xl); + y = uint63_of_value(y); uint64_t maskh = 0; uint64_t maskl = 1; uint64_t dh = 0; - uint64_t dl = (uint64_t)y >> 1; + uint64_t dl = y; int cmp = 1; - while (dh >= 0 && cmp) { + /* int n = 0 */ + /* loop invariant: mask = 2^n, d = mask * y, (2 * d <= x -> cmp), n >= 0, d < 2^(2*63) */ + while (!(dh >> (63 - 1)) && cmp) { + dh = (dh << 1) | (dl >> (63 - 1)); + dl = (dl << 1) & maxuint63; + maskh = (maskh << 1) | (maskl >> (63 - 1)); + maskl = (maskl << 1) & maxuint63; + /* ++n */ cmp = lt128(dh,dl,xh,xl); - dh = (dh << 1) | (dl >> 63); - dl = dl << 1; - maskh = (maskh << 1) | (maskl >> 63); - maskl = maskl << 1; } uint64_t remh = xh; uint64_t reml = xl; - uint64_t quotient = 0; + /* uint64_t quotienth = 0; */ + uint64_t quotientl = 0; + /* loop invariant: x = quotient * y + rem, y * 2^(n+1) > r, + mask = floor(2^n), d = mask * y, n >= -1 */ while (maskh | maskl) { - if (le128(dh,dl,remh,reml)) { - quotient = quotient | maskl; - if (uint63_lt(reml,dl)) {remh = remh - dh - 1;} else {remh = remh - dh;} + if (le128(dh,dl,remh,reml)) { /* if rem >= d, add one bit and subtract d */ + /* quotienth = quotienth | maskh */ + quotientl = quotientl | maskl; + remh = (uint63_lt(reml,dl)) ? (remh - dh - 1) : (remh - dh); reml = reml - dl; } - maskl = (maskl >> 1) | (maskh << 63); + maskl = (maskl >> 1) | ((maskh << (63 - 1)) & maxuint63); maskh = maskh >> 1; - dl = (dl >> 1) | (dh << 63); + dl = (dl >> 1) | ((dh << (63 - 1)) & maxuint63); dh = dh >> 1; + /* decr n */ } - *q = Val_int(quotient); + *ql = Val_int(quotientl); return Val_int(reml); } +value uint63_div21(value xh, value xl, value y, value* ql) { + if (uint63_of_value(y) == 0) { + *ql = Val_int(0); + return Val_int(0); + } else { + return uint63_div21_aux(xh, xl, y, ql); + } +} #define Uint63_div21(xh, xl, y, q) (accu = uint63_div21(xh, xl, y, q)) |